1
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Sauer EL, Venesky MD, McMahon TA, Cohen JM, Bessler S, Brannelly LA, Brem F, Byrne AQ, Halstead N, Hyman O, Johnson PTJ, Richards-Zawacki CL, Rumschlag SL, Sears B, Rohr JR. Are novel or locally adapted pathogens more devastating and why? Resolving opposing hypotheses. Ecol Lett 2024; 27:e14431. [PMID: 38712705 DOI: 10.1111/ele.14431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 05/08/2024]
Abstract
There is a rich literature highlighting that pathogens are generally better adapted to infect local than novel hosts, and a separate seemingly contradictory literature indicating that novel pathogens pose the greatest threat to biodiversity and public health. Here, using Batrachochytrium dendrobatidis, the fungus associated with worldwide amphibian declines, we test the hypothesis that there is enough variance in "novel" (quantified by geographic and phylogenetic distance) host-pathogen outcomes to pose substantial risk of pathogen introductions despite local adaptation being common. Our continental-scale common garden experiment and global-scale meta-analysis demonstrate that local amphibian-fungal interactions result in higher pathogen prevalence, pathogen growth, and host mortality, but novel interactions led to variable consequences with especially virulent host-pathogen combinations still occurring. Thus, while most pathogen introductions are benign, enough variance exists in novel host-pathogen outcomes that moving organisms around the planet greatly increases the chance of pathogen introductions causing profound harm.
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Affiliation(s)
- Erin L Sauer
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USA
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Matthew D Venesky
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
- Department of Biology, Allegheny College, Meadville, Pennsylvania, USA
| | - Taegan A McMahon
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
- Biology Department, Connecticut College, New London, Connecticut, USA
| | - Jeremy M Cohen
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
| | - Scott Bessler
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Laura A Brannelly
- Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, USA
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Forrest Brem
- Biology Department, University of Memphis, Memphis, Tennessee, USA
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA
| | - Neal Halstead
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
- Wildlands Conservation, Tampa, Florida, USA
| | - Oliver Hyman
- Biology Department, James Madison University, Harrisonburg, Virginia, USA
| | - Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
| | - Corinne L Richards-Zawacki
- Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Samantha L Rumschlag
- Department of Biology, Miami University, Oxford, Ohio, USA
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, Minnesota, USA
| | - Brittany Sears
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
- Department of Biological Sciences, University of Notre Dame, South Bend, Indiana, USA
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2
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Robak MJ, Saenz V, de Cortie E, Richards-Zawacki CL. Effects of temperature on the interaction between amphibian skin bacteria and Batrachochytrium dendrobatidis. Front Microbiol 2023; 14:1253482. [PMID: 37942072 PMCID: PMC10628663 DOI: 10.3389/fmicb.2023.1253482] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023] Open
Abstract
Symbiotic relationships between animals and microbes are important for a range of functions, from digestion to protection from pathogens. However, the impact of temperature variation on these animal-microbe interactions remains poorly understood. Amphibians have experienced population declines and even extinctions on a global scale due to chytridiomycosis, a disease caused by chytrid fungi in the genus Batrachochytrium. Variation in susceptibility to this disease exists within and among host species. While the mechanisms generating differences in host susceptibility remain elusive, differences in immune system components, as well as variation in host and environmental temperatures, have been associated with this variation. The symbiotic cutaneous bacteria of amphibians are another potential cause for variation in susceptibility to chytridiomycosis, with some bacterial species producing antifungal metabolites that prevent the growth of Bd. The growth of both Bd and bacteria are affected by temperature, and thus we hypothesized that amphibian skin bacteria may be more effective at preventing Bd growth at certain temperatures. To test this, we collected bacteria from the skins of frogs, harvested the metabolites they produced when grown at three different temperatures, and then grew Bd in the presence of those metabolites under those same three temperatures in a three-by-three fully crossed design. We found that both the temperature at which cutaneous bacteria were grown (and metabolites produced) as well as the temperature at which Bd is grown can impact the ability of cutaneous bacteria to inhibit the growth of Bd. While some bacterial isolates showed the ability to inhibit Bd growth across multiple temperature treatments, no isolate was found to be inhibitive across all combinations of bacterial incubation or Bd challenge temperatures, suggesting that temperature affects both the metabolites produced and the effectiveness of those metabolites against the Bd pathogen. These findings move us closer to a mechanistic understanding of why chytridiomycosis outbreaks and related amphibian declines are often limited to certain climates and seasons.
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Affiliation(s)
- Matthew J. Robak
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, United States
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Biology, The Pennsylvania State University, State College, PA, United States
| | - Esmee de Cortie
- Falk School of Sustainability and Environment, Chatham University, Pittsburgh, PA, United States
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3
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Wan YC, Navarrete Méndez MJ, O'Connell LA, Uricchio LH, Roland AB, Maan ME, Ron SR, Betancourth-Cundar M, Pie MR, Howell KA, Richards-Zawacki CL, Cummings ME, Cannatella DC, Santos JC, Tarvin RD. Selection on Visual Opsin Genes in Diurnal Neotropical Frogs and Loss of the SWS2 Opsin in Poison Frogs. Mol Biol Evol 2023; 40:msad206. [PMID: 37791477 PMCID: PMC10548314 DOI: 10.1093/molbev/msad206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023] Open
Abstract
Amphibians are ideal for studying visual system evolution because their biphasic (aquatic and terrestrial) life history and ecological diversity expose them to a broad range of visual conditions. Here, we evaluate signatures of selection on visual opsin genes across Neotropical anurans and focus on three diurnal clades that are well-known for the concurrence of conspicuous colors and chemical defense (i.e., aposematism): poison frogs (Dendrobatidae), Harlequin toads (Bufonidae: Atelopus), and pumpkin toadlets (Brachycephalidae: Brachycephalus). We found evidence of positive selection on 44 amino acid sites in LWS, SWS1, SWS2, and RH1 opsin genes, of which one in LWS and two in RH1 have been previously identified as spectral tuning sites in other vertebrates. Given that anurans have mostly nocturnal habits, the patterns of selection revealed new sites that might be important in spectral tuning for frogs, potentially for adaptation to diurnal habits and for color-based intraspecific communication. Furthermore, we provide evidence that SWS2, normally expressed in rod cells in frogs and some salamanders, has likely been lost in the ancestor of Dendrobatidae, suggesting that under low-light levels, dendrobatids have inferior wavelength discrimination compared to other frogs. This loss might follow the origin of diurnal activity in dendrobatids and could have implications for their behavior. Our analyses show that assessments of opsin diversification in across taxa could expand our understanding of the role of sensory system evolution in ecological adaptation.
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Affiliation(s)
- Yin Chen Wan
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - María José Navarrete Méndez
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- Museo de Zoología, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | | | - Lawrence H Uricchio
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- Department of Biology, Tufts University, Medford, MA, USA
| | - Alexandre-Benoit Roland
- FAS Center for Systems Biology, Harvard University, Cambridge, MA, USA
- Research Centre on Animal Cognition (CRCA), Centre for Integrative Biology (CBI), UMR5169 CNRS, Toulouse University, Toulouse, France
| | - Martine E Maan
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Santiago R Ron
- Museo de Zoología, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | | | - Marcio R Pie
- Department of Zoology, Universidade Federal do Paraná, Curitiba, Brazil
- Biology Department, Edge Hill University, Ormskirk, United Kingdom
| | - Kimberly A Howell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Molly E Cummings
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - David C Cannatella
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
- Biodiversity Center, University of Texas at Austin, Austin, TX, USA
| | - Juan C Santos
- Department of Biological Sciences, St. John's University, New York City, NY, USA
| | - Rebecca D Tarvin
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
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4
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Verble RM, Richards-Zawacki CL, Young VKH. Beyond A Vision for The Future: Tangible Steps To Engage Diverse Participants in Inclusive Field Experiences. Integr Comp Biol 2023:icad063. [PMID: 37312281 DOI: 10.1093/icb/icad063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023] Open
Abstract
Recent strides toward improving diversity, equity, and inclusion (DEI) in field biology present a unique opportunity for transdisciplinary exploration of the impacts and state of a topic that has remained hereto largely underexplored and under-discussed in the academic setting. Within current literature, themes of racial and gender inequity, power imbalances, unsafe environments, and underdeveloped infrastructure and resources are widespread. Thus, we organized a symposium that addressed these compelling issues in field biology DEI through a multitude of experiential and academic lenses. This article will orient the reader to the special issue and offer summative goals and outcomes of the symposium that can provide tangible steps toward creating meaningful improvements in the state of DEI and safety in field settings.
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Affiliation(s)
- Robin M Verble
- Associate Professor of Biological Science, Director of Environmental Science Program and Ozark Research Field Station, Missouri University of Science and Technology
| | - Corinne L Richards-Zawacki
- Professor of Biological Sciences and Director of Pymatuning Laboratory of Ecology, University of Pittsburgh
| | - Vanessa K H Young
- Associate Professor of Biology, Saint Mary's College, Notre Dame, Indiana
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5
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Ohmer MEB, Hammond TT, Switzer S, Wantman T, Bednark JG, Paciotta E, Coscia J, Richards-Zawacki CL. Developmental environment has lasting effects on amphibian post-metamorphic behavior and thermal physiology. J Exp Biol 2023; 226:309346. [PMID: 37039737 DOI: 10.1242/jeb.244883] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 03/21/2023] [Indexed: 04/12/2023]
Abstract
Environmental challenges early in development can result in complex phenotypic trade-offs and long-term effects on individual physiology, performance, and behavior, with implications for disease and predation risk. We examined the effects of simulated pond-drying and elevated water temperatures on development, growth, thermal physiology, and behavior in a North American amphibian, Rana sphenocephala. Tadpoles were raised in outdoor mesocosms under warming and drying regimes based on projected climatic conditions in 2070. We predicted that amphibians experiencing the rapid pond drying and elevated pond temperatures associated with climate change would accelerate development, be smaller at metamorphosis and demonstrate long-term differences in physiology and exploratory behavior post-metamorphosis. While both drying and warming accelerated development and reduced survival to metamorphosis, only drying resulted in smaller animals at metamorphosis. Around one-month post-metamorphosis, animals from the control treatment jumped relatively farther at high temperatures in jumping trials. In addition, across all treatments, frogs with shorter larval periods had lower critical thermal minima and maxima. We also found that developing under warming and drying resulted in a less exploratory behavioral phenotype, and that drying resulted in higher selected temperatures in a thermal gradient. Furthermore, behavior predicted thermal preference, with less exploratory animals selecting higher temperatures. Our results underscore the multi-faceted effects of early developmental environments on behavioral and physiological phenotypes later in life. Thermal preference can influence disease risk through behavioral thermoregulation, and exploratory behavior may increase risk of predation or pathogen encounter. Thus, climatic stressors during development may mediate amphibian exposure and susceptibility to predators and pathogens into later life stages.
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Affiliation(s)
- Michel E B Ohmer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Dept. of Biology, University of Mississippi, University, MS, USA
| | - Talisin T Hammond
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Samantha Switzer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Trina Wantman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Dept. of Biology, University of Mississippi, University, MS, USA
| | - Jeffery G Bednark
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Dept. of Psychology, University of Mississippi, University, MS, USA
| | - Emilie Paciotta
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jordan Coscia
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, USA
- Virginia Working Landscapes, Smithsonian Conservation Biology Institute, Front Royal, VA, USA
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6
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Yeager J, Derryberry GE, Blum MJ, Richards-Zawacki CL. Selection and Admixture in a Polytypic Aposematic Frog. Am Nat 2023; 201:215-228. [PMID: 36724462 DOI: 10.1086/722559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AbstractPhenotypic differentiation within polytypic species is often attributed to selection, particularly when selection might be acting on a trait that serves as a signal for predator avoidance and mate choice. We evaluated this hypothesis by examining phenotypic and genotypic clines between populations of the strawberry poison frog Oophaga pumilio, a polytypic species that exhibits aposematic color pattern variation that is thought to be subject to both natural and sexual selection. Our aim was to assess the extent of admixture and to estimate the strength of selection acting on coloration across a region of Panama where monomorphic populations of distinctly colored frogs are separated by polymorphic populations containing both color variants alongside intermediately colored individuals. We detected sharp clinal transitions across the study region, which is an expected outcome of strong selection, but we also detected evidence of widespread admixture, even at sites far from the phenotypic transition zone. Additionally, genotypic and phenotypic clines were neither concordant nor coincident, and with one exception, selection coefficients estimated from cline attributes were small. These results suggest that strong selection is not required for the maintenance of phenotypic divergence within polytypic species, challenging the long-standing notion that strong selection is implicit in the evolution of warning signals.
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7
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Chatfield MWH, Moler P, Richards-Zawacki CL. Correction: The Amphibian Chytrid Fungus, Batrachochytrium dendrobatidis, in Fully Aquatic Salamanders from Southeastern North America. PLoS One 2022; 17:e0271363. [PMID: 35802603 PMCID: PMC9269427 DOI: 10.1371/journal.pone.0271363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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8
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Wilber MQ, Ohmer MEB, Altman KA, Brannelly LA, LaBumbard BC, Le Sage EH, McDonnell NB, Muñiz Torres AY, Nordheim CL, Pfab F, Richards-Zawacki CL, Rollins-Smith LA, Saenz V, Voyles J, Wetzel DP, Woodhams DC, Briggs CJ. Once a reservoir, always a reservoir? Seasonality affects the pathogen maintenance potential of amphibian hosts. Ecology 2022; 103:e3759. [PMID: 35593515 DOI: 10.1002/ecy.3759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/18/2022] [Accepted: 03/31/2022] [Indexed: 11/10/2022]
Abstract
Host species that can independently maintain a pathogen in a host community and contribute to infection in other species are important targets for disease management. However, the potential of host species to maintain a pathogen is not fixed over time, and an important challenge is understanding how within- and across-season variability in host maintenance potential affects pathogen persistence over longer time scales relevant for disease management (e.g., years). Here, we sought to understand the causes and consequences of seasonal infection dynamics in leopard frogs (Rana sphenocephala and R. pipiens) infected with the fungal pathogen Batrachochytrium dendrobatidis (Bd). We addressed three questions broadly applicable to seasonal host-parasite systems. First, to what degree are observed seasonal patterns in infection driven by temperature-dependent infection processes compared to seasonal host demographic processes? Second, how does seasonal variation in maintenance potential affect long-term pathogen persistence in multihost communities? Third, does high deterministic maintenance potential relate to the long-term stochastic persistence of pathogens in host populations with seasonal infection dynamics? To answer these questions, we used field data collected over three years on >1400 amphibians across four geographic locations, laboratory and mesocosm experiments, and a novel mathematical model. We found that the mechanisms that drive seasonal prevalence were different than those driving seasonal infection intensity. Seasonal variation in Bd prevalence was driven primarily by changes in host contact rates associated with breeding migrations to and from aquatic habitat. In contrast, seasonal changes in infection intensity were driven by temperature-induced changes in Bd growth rate. Using our model, we found that the maintenance potential of leopard frogs varied significantly throughout the year and that seasonal troughs in infection prevalence made it unlikely that leopard frogs were responsible for long-term Bd persistence in these seasonal amphibian communities, highlighting the importance of alternative pathogen reservoirs for Bd persistence. Our results have broad implications for management in seasonal host-pathogen systems, showing that seasonal changes in host and pathogen vital rates, rather than the depletion of susceptible hosts, can lead to troughs in pathogen prevalence and stochastic pathogen extirpation.
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Affiliation(s)
- Mark Q Wilber
- Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Institute of Agriculture, Knoxville, TN.,Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Michel E B Ohmer
- Living Earth Collaborative, Washington University in St. Louis, St. Louis, MO.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, University of Mississippi, Oxford, MS
| | - Karie A Altman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, St. Bonaventure University, St Bonaventure, NY
| | - Laura A Brannelly
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Brandon C LaBumbard
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Emily H Le Sage
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Nina B McDonnell
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Aura Y Muñiz Torres
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Caitlin L Nordheim
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Ferdinand Pfab
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | | | - Louise A Rollins-Smith
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, Reno, NV
| | - Daniel P Wetzel
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
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9
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Byrne AQ, Waddle AW, Saenz V, Ohmer M, Jaeger JR, Richards-Zawacki CL, Voyles J, Rosenblum EB. Host species is linked to pathogen genotype for the amphibian chytrid fungus (Batrachochytrium dendrobatidis). PLoS One 2022; 17:e0261047. [PMID: 35286323 PMCID: PMC8920232 DOI: 10.1371/journal.pone.0261047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/01/2022] [Indexed: 11/21/2022] Open
Abstract
Host-pathogen specificity can arise from certain selective environments mediated by both the host and pathogen. Therefore, understanding the degree to which host species identity is correlated with pathogen genotype can help reveal historical host-pathogen dynamics. One animal disease of particular concern is chytridiomycosis, typically caused by the global panzootic lineage of the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd), termed Bd-GPL. This pathogen lineage has caused devastating declines in amphibian communities around the world. However, the site of origin for the common ancestor of modern Bd-GPL and the fine-scale transmission dynamics of this lineage have remained a mystery. This is especially the case in North America where Bd-GPL is widespread, but disease outbreaks occur sporadically. Herein, we use Bd genetic data collected throughout the United States from amphibian skin swabs and cultured isolate samples to investigate Bd genetic patterns. We highlight two case studies in Pennsylvania and Nevada where Bd-GPL genotypes are strongly correlated with host species identity. Specifically, in some localities bullfrogs (Rana catesbeiana) are infected with Bd-GPL lineages that are distinct from those infecting other sympatric amphibian species. Overall, we reveal a previously unknown association of Bd genotype with host species and identify the eastern United States as a Bd diversity hotspot and potential site of origin for Bd-GPL.
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Affiliation(s)
- Allison Q. Byrne
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, California, United States of America
- * E-mail:
| | - Anthony W. Waddle
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, United States of America
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Michel Ohmer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Biology, University of Mississippi, Oxford, Mississippi, United States of America
| | - Jef R. Jaeger
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, United States of America
| | - Corinne L. Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jamie Voyles
- Department of Biology, University of Nevada Reno, Reno, Nevada, United States of America
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, California, United States of America
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10
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Rothstein AP, Byrne AQ, Knapp RA, Briggs CJ, Voyles J, Richards-Zawacki CL, Rosenblum EB. Divergent regional evolutionary histories of a devastating global amphibian pathogen. Proc Biol Sci 2021; 288:20210782. [PMID: 34157877 PMCID: PMC8220259 DOI: 10.1098/rspb.2021.0782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Emerging infectious diseases are a pressing threat to global biological diversity. Increased incidence and severity of novel pathogens underscores the need for methodological advances to understand pathogen emergence and spread. Here, we use genetic epidemiology to test, and challenge, key hypotheses about a devastating zoonotic disease impacting amphibians globally. Using an amplicon-based sequencing method and non-invasive samples we retrospectively explore the history of the fungal pathogen Batrachochytrium dendrobatidis (Bd) in two emblematic amphibian systems: the Sierra Nevada of California and Central Panama. The hypothesis in both regions is the hypervirulent Global Panzootic Lineage of Bd (BdGPL) was recently introduced and spread rapidly in a wave-like pattern. Our data challenge this hypothesis by demonstrating similar epizootic signatures can have radically different underlying evolutionary histories. In Central Panama, our genetic data confirm a recent and rapid pathogen spread. However, BdGPL in the Sierra Nevada has remarkable spatial structuring, high genetic diversity and a relatively older history inferred from time-dated phylogenies. Thus, this deadly pathogen lineage may have a longer history in some regions than assumed, providing insights into its origin and spread. Overall, our results highlight the importance of integrating observed wildlife die-offs with genetic data to more accurately reconstruct pathogen outbreaks.
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Affiliation(s)
- Andrew P Rothstein
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA.,Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA
| | - Roland A Knapp
- Sierra Nevada Aquatic Research Laboratory, University of California, Mammoth Lakes, CA, USA.,Earth Research Institute, University of California, Santa Barbara, CA, USA
| | - Cheryl J Briggs
- Earth Research Institute, University of California, Santa Barbara, CA, USA.,Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV, USA
| | | | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
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11
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Sheets CN, Schmidt DR, Hurtado PJ, Byrne AQ, Rosenblum EB, Richards-Zawacki CL, Voyles J. Thermal Performance Curves of Multiple Isolates of Batrachochytrium dendrobatidis, a Lethal Pathogen of Amphibians. Front Vet Sci 2021; 8:687084. [PMID: 34239916 PMCID: PMC8258153 DOI: 10.3389/fvets.2021.687084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/20/2021] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious disease is a key factor in the loss of amphibian diversity. In particular, the disease chytridiomycosis has caused severe declines around the world. The lethal fungal pathogen that causes chytridiomycosis, Batrachochytrium dendrobatidis (Bd), has affected amphibians in many different environments. One primary question for researchers grappling with disease-induced losses of amphibian biodiversity is what abiotic factors drive Bd pathogenicity in different environments. To study environmental influences on Bd pathogenicity, we quantified responses of Bd phenotypic traits (e.g., viability, zoospore densities, growth rates, and carrying capacities) over a range of environmental temperatures to generate thermal performance curves. We selected multiple Bd isolates that belong to a single genetic lineage but that were collected across a latitudinal gradient. For the population viability, we found that the isolates had similar thermal optima at 21°C, but there was considerable variation among the isolates in maximum viability at that temperature. Additionally, we found the densities of infectious zoospores varied among isolates across all temperatures. Our results suggest that temperatures across geographic point of origin (latitude) may explain some of the variation in Bd viability through vertical shifts in maximal performance. However, the same pattern was not evident for other reproductive parameters (zoospore densities, growth rates, fecundity), underscoring the importance of measuring multiple traits to understand variation in pathogen responses to environmental conditions. We suggest that variation among Bd genetic variants due to environmental factors may be an important determinant of disease dynamics for amphibians across a range of diverse environments.
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Affiliation(s)
- Ciara N Sheets
- Department of Biology, University of Nevada, Reno, NV, United States
| | - Deena R Schmidt
- Department of Mathematics and Statistics, University of Nevada, Reno, NV, United States
| | - Paul J Hurtado
- Department of Mathematics and Statistics, University of Nevada, Reno, NV, United States
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United States.,Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United States.,Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
| | | | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV, United States
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12
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Byrne AQ, Richards-Zawacki CL, Voyles J, Bi K, Ibáñez R, Rosenblum EB. Whole exome sequencing identifies the potential for genetic rescue in iconic and critically endangered Panamanian harlequin frogs. Glob Chang Biol 2021; 27:50-70. [PMID: 33150627 DOI: 10.1111/gcb.15405] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/24/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Avoiding extinction in a rapidly changing environment often relies on a species' ability to quickly adapt in the face of extreme selective pressures. In Panamá, two closely related harlequin frog species (Atelopus varius and Atelopus zeteki) are threatened with extinction due to the fungal pathogen Batrachochytrium dendrobatidis (Bd). Once thought to be nearly extirpated from Panamá, A. varius have recently been rediscovered in multiple localities across their historical range; however, A. zeteki are possibly extinct in the wild. By leveraging a unique collection of 186 Atelopus tissue samples collected before and after the Bd outbreak in Panama, we describe the genetics of persistence for these species on the brink of extinction. We sequenced the transcriptome and developed an exome-capture assay to sequence the coding regions of the Atelopus genome. Using these genetic data, we evaluate the population genetic structure of historical A. varius and A. zeteki populations, describe changes in genetic diversity over time, assess the relationship between contemporary and historical individuals, and test the hypothesis that some A. varius populations have rapidly evolved to resist or tolerate Bd infection. We found a significant decrease in genetic diversity in contemporary (compared to historical) A. varius populations. We did not find strong evidence of directional allele frequency change or selection for Bd resistance genes, but we uncovered a set of candidate genes that warrant further study. Additionally, we found preliminary evidence of recent migration and gene flow in one of the largest persisting A. varius populations in Panamá, suggesting the potential for genetic rescue in this system. Finally, we propose that previous conservation units should be modified, as clear genetic breaks do not exist beyond the local population level. Our data lay the groundwork for genetically informed conservation and advance our understanding of how imperiled species might be rescued from extinction.
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Affiliation(s)
- Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | | | - Jamie Voyles
- Department of Biology, University of Nevada Reno, Reno, NV, USA
| | - Ke Bi
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Roberto Ibáñez
- Smithsonian Tropical Research Institute, Panamá, República de Panamá
- Sistema Nacional de Investigación, SENACYT, Clayton, Panamá, República de Panamá
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
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13
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Ohmer MEB, Costantini D, Czirják GÁ, Downs CJ, Ferguson LV, Flies A, Franklin CE, Kayigwe AN, Knutie S, Richards-Zawacki CL, Cramp RL. Applied ecoimmunology: using immunological tools to improve conservation efforts in a changing world. Conserv Physiol 2021; 9:coab074. [PMID: 34512994 PMCID: PMC8422949 DOI: 10.1093/conphys/coab074] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 07/27/2021] [Accepted: 08/09/2021] [Indexed: 05/11/2023]
Abstract
Ecoimmunology is a rapidly developing field that explores how the environment shapes immune function, which in turn influences host-parasite relationships and disease outcomes. Host immune defence is a key fitness determinant because it underlies the capacity of animals to resist or tolerate potential infections. Importantly, immune function can be suppressed, depressed, reconfigured or stimulated by exposure to rapidly changing environmental drivers like temperature, pollutants and food availability. Thus, hosts may experience trade-offs resulting from altered investment in immune function under environmental stressors. As such, approaches in ecoimmunology can provide powerful tools to assist in the conservation of wildlife. Here, we provide case studies that explore the diverse ways that ecoimmunology can inform and advance conservation efforts, from understanding how Galapagos finches will fare with introduced parasites, to using methods from human oncology to design vaccines against a transmissible cancer in Tasmanian devils. In addition, we discuss the future of ecoimmunology and present 10 questions that can help guide this emerging field to better inform conservation decisions and biodiversity protection. From better linking changes in immune function to disease outcomes under different environmental conditions, to understanding how individual variation contributes to disease dynamics in wild populations, there is immense potential for ecoimmunology to inform the conservation of imperilled hosts in the face of new and re-emerging pathogens, in addition to improving the detection and management of emerging potential zoonoses.
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Affiliation(s)
- Michel E B Ohmer
- Living Earth Collaborative, Washington University in St. Louis, MO 63130, USA
| | - David Costantini
- Unité Physiologie Moléculaire et Adaptation (PhyMA), Muséum National d’Histoire Naturelle, CNRS, 57 Rue Cuvier, CP32, 75005, Paris, France
| | - Gábor Á Czirják
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, 10315 Berlin, Germany
| | - Cynthia J Downs
- Department of Environmental Biology, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210, USA
| | - Laura V Ferguson
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Andy Flies
- Menzies Institute for Medical Research, University of Tasmania, Tasmania 7001, Australia
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Queensland 4072, Australia
| | - Ahab N Kayigwe
- Menzies Institute for Medical Research, University of Tasmania, Tasmania 7001, Australia
| | - Sarah Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06268, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT 06268, USA
| | | | - Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Queensland 4072, Australia
- Corresponding author: School of Biological Sciences, The University of Queensland, Queensland 4072, Australia.
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14
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Sonn JM, Porter WP, Mathewson PD, Richards-Zawacki CL. Predictions of Disease Risk in Space and Time Based on the Thermal Physiology of an Amphibian Host-Pathogen Interaction. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.576065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious diseases have been responsible for declines and extinctions in a growing number of species. Predicting disease variables like infection prevalence and mortality and how they vary in space and time will be critical to understanding how host-pathogen dynamics play out in natural environments and will help to inform management actions. The pandemic disease chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been implicated in declines in hundreds of amphibian species worldwide. We used field-collected measurements of host body temperatures and other physiological parameters to develop a mechanistic model of disease risk in a declining amphibian, the Northern cricket frog (Acris crepitans). We first used a biophysical model to predict host body temperatures across the species range in the eastern United States. We then used empirically derived relationships between host body temperature, infection prevalence and survival to predict where and when the risk of Bd-related declines is greatest. Our model predicts that pathogen prevalence is greatest, and survival of infected A. crepitans frogs is lowest, just prior to breeding when host body temperatures are low. Taken together, these results suggest that Bd poses the greatest threat to short-lived A. crepitans populations in the northern part of this host’s range and that disease-related recruitment failure may be common. Furthermore, our study demonstrates the utility of mechanistic modeling approaches for predicting disease outbreaks and dynamics in animal hosts.
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15
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Le Sage EH, LaBumbard BC, Reinert LK, Miller BT, Richards-Zawacki CL, Woodhams DC, Rollins-Smith LA. Preparatory immunity: Seasonality of mucosal skin defences and Batrachochytrium infections in Southern leopard frogs. J Anim Ecol 2020; 90:542-554. [PMID: 33179786 DOI: 10.1111/1365-2656.13386] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/28/2020] [Indexed: 12/14/2022]
Abstract
Accurately predicting the impacts of climate change on wildlife health requires a deeper understanding of seasonal rhythms in host-pathogen interactions. The amphibian pathogen, Batrachochytrium dendrobatidis (Bd), exhibits seasonality in incidence; however, the role that biological rhythms in host defences play in defining this pattern remains largely unknown. The aim of this study was to examine whether host immune and microbiome defences against Bd correspond with infection risk and seasonal fluctuations in temperature and humidity. Over the course of a year, five populations of Southern leopard frogs (Rana [Lithobates] sphenocephala) in Tennessee, United States, were surveyed for host immunity, microbiome and pathogen dynamics. Frogs were swabbed for pathogen load and skin bacterial diversity and stimulated to release stored antimicrobial peptides (AMPs). Secretions were analysed to estimate total hydrophobic peptide concentrations, presence of known AMPs and effectiveness of Bd growth inhibition in vitro. The diversity and proportion of bacterial reads with a 99% match to sequences of isolates known to inhibit Bd growth in vitro were used as an estimate of predicted anti-Bd function of the skin microbiome. Batrachochytrium dendrobatidis dynamics followed the expected seasonal fluctuations-peaks in cooler months-which coincided with when host mucosal defences were most potent against Bd. Specifically, the concentration and expression of stored AMPs cycled synchronously with Bd dynamics. Although microbiome changes followed more linear trends over time, the proportion of bacteria that can function to inhibit Bd growth was greatest when risk of Bd infection was highest. We interpret the increase in peptide storage in the fall and the shift to a more anti-Bd microbiome over winter as a preparatory response for subsequent infection risk during the colder periods when AMP synthesis and bacterial growth is slow and pathogen pressure from this cool-adapted fungus is high. Given that a decrease in stored AMP concentrations as temperatures warm in spring likely means greater secretion rates, the subsequent decrease in prevalence suggests seasonality of Bd in this host may be in part regulated by annual immune rhythms, and dominated by the effects of temperature.
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Affiliation(s)
- Emily H Le Sage
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - Laura K Reinert
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brian T Miller
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, USA
| | | | - Doug C Woodhams
- Department of Biology, University of Massachusetts, Boston, MA, USA
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.,Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.,Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA
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16
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Abstract
Abstract
Codivergence of sexual traits and mate preferences can lead to assortative mating and subsequently reproductive isolation. However, mate choice rarely operates without intrasexual competition, and the effects of the latter on speciation are often overlooked. Maintaining trait polymorphisms despite gene flow and limiting assortative female preferences for less-competitive male phenotypes are two important roles that male–male competition may play in the speciation process. Both roles rely on the assumption that male–male competition limits the expression of divergent female preferences. We tested this assumption in the highly color-polymorphic strawberry poison frog (Oophaga pumilio). Females prefer males of the local color, suggesting that reproductive isolation may be evolving among color morphs. However, this inference does not account for male–male competition, which is also color-mediated. We housed females with two differently colored males, and compared reproductive patterns when the more attractive male was the territory holder versus when he was the nonterritorial male. Females mated primarily with the territory winner, regardless of coloration, suggesting that when a choice must be made between the two, male territoriality overrides female preferences for male coloration. Our results highlight the importance of considering the combined effects of mate choice and intrasexual competition in shaping phenotypic divergence and speciation.
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Affiliation(s)
- Yusan Yang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Smithsonian Tropical Research Institute Tupper, Balboa, Ancon, Panama, Republic of Panama
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17
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Brannelly LA, Wetzel DP, Ohmer MEB, Zimmerman L, Saenz V, Richards-Zawacki CL. Evaluating environmental DNA as a tool for detecting an amphibian pathogen using an optimized extraction method. Oecologia 2020; 194:267-281. [PMID: 32880026 DOI: 10.1007/s00442-020-04743-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 08/26/2020] [Indexed: 12/29/2022]
Abstract
Environmental DNA (eDNA) detection is a valuable conservation tool that can be used to identify and monitor imperiled or invasive species and wildlife pathogens. Batrachochytrium pathogens are of global conservation concern because they are a leading cause of amphibian decline. While eDNA techniques have been used to detect Batrachochytrium DNA in the environment, a systematic comparison of extraction methods across environmental samples is lacking. In this study, we first compared eDNA extraction methods and found that a soil extraction kit (Qiagen PowerSoil) was the most effective for detecting Batrachochytrium dendrobatidis in water samples. The PowerSoil extraction had a minimum detection level of 100 zoospores and had a two- to four-fold higher detection probability than other commonly used extraction methods (e.g., QIAamp extraction, DNeasy+Qiashredder extraction method, respectively). Next, we used this extraction method on field-collected water and sediment samples and were able to detect pathogen DNA in both. While field-collected water filters were equivalent to amphibian skin swab samples in detecting the presence of pathogen DNA, the seasonal patterns in pathogen quantity were different between skin swabs and water samples. Detection rate was lowest in sediment samples. We also found that detection probability increases with the volume of water filtered. Our results indicate that water filter eDNA samples can be accurate in detecting pathogen presence at the habitat scale but their utility for quantifying pathogen loads in the environment appears limited. We suggest that eDNA techniques be used for early warning detection to guide animal sampling efforts.
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Affiliation(s)
- Laura A Brannelly
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA. .,Melbourne Veterinary School, Faculty of Agricultural and Veterinary Sciences, University of Melbourne, Werribee, VIC, Australia.
| | - Daniel P Wetzel
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michel E B Ohmer
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lydia Zimmerman
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Veronica Saenz
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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18
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Brannelly LA, Wetzel DP, West M, Richards-Zawacki CL. Optimized Batrachochytrium dendrobatidis DNA extraction of swab samples results in imperfect detection particularly when infection intensities are low. Dis Aquat Organ 2020; 139:233-243. [PMID: 32495749 DOI: 10.3354/dao03482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Accurate detection of the amphibian fungal pathogen Batrachochytrium dendrobatidis (Bd) is critical for wildlife disease research; however, false negatives in detection do occur. Here we compared different DNA extraction methods to determine the threshold for Bd detection and identify an optimal extraction method to improve detection and quantification of the pathogen. We extracted both lab-created cell suspension standards using PrepMan Ultra, Chelex resin, and 3 spin column DNA extraction kits (Qiagen DNeasy Blood and Tissue, Zymo Quick DNA miniprep, and IBI gMAX mini kit), and further compared extraction methods using field-collected samples. We found that when extracting Bd DNA from cells in lab-created culture, the spin column extraction methods and PrepMan Ultra were equivalent, while the resin method detected higher Bd DNA quantities, especially at higher loads. However, when swabs from live animals were analyzed, low Bd quantities were more than twice as likely to be detected using a spin column extraction than with the PrepMan Ultra extraction method. All tested spin column extraction methods performed similarly across both field and lab samples. Samples containing low Bd quantities yielded inconsistent detection and quantification of Bd DNA copies regardless of extraction method. To manage imperfect detection of Bd, we suggest that presence/absence analyses are more informative than attempting to quantify Bd DNA when quantities are low. Overall, we recommend that a cost-benefit analysis of target species susceptibility and epidemiology be taken into consideration when designing an experiment to determine the most appropriate DNA extraction method to be used, because sometimes detecting low Bd quantities is imperative to the study, whereas in other situations, detecting low DNA quantities is less important.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Victoria 3030, Australia
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19
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Scheele BC, Pasmans F, Skerratt LF, Berger L, Martel A, Beukema W, Acevedo AA, Burrowes PA, Carvalho T, Catenazzi A, De la Riva I, Fisher MC, Flechas SV, Foster CN, Frías-Álvarez P, Garner TWJ, Gratwicke B, Guayasamin JM, Hirschfeld M, Kolby JE, Kosch TA, La Marca E, Lindenmayer DB, Lips KR, Longo AV, Maneyro R, McDonald CA, Mendelson J, Palacios-Rodriguez P, Parra-Olea G, Richards-Zawacki CL, Rödel MO, Rovito SM, Soto-Azat C, Toledo LF, Voyles J, Weldon C, Whitfield SM, Wilkinson M, Zamudio KR, Canessa S. Response to Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity". Science 2020; 367:367/6484/eaay2905. [PMID: 32193294 DOI: 10.1126/science.aay2905] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 02/20/2020] [Indexed: 01/03/2023]
Abstract
Lambert et al question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in amphibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and hampers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 amphibian species.
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Affiliation(s)
- Ben C Scheele
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia. .,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia.,One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia
| | - Frank Pasmans
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Lee F Skerratt
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia
| | - Lee Berger
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia
| | - An Martel
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Wouter Beukema
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Aldemar A Acevedo
- Programa de Doctorado en Ciencias Biológicas, Laboratorio de Biología Evolutiva, Pontificia Universidad Católica de Chile, Santiago, Chile.,Grupo de Investigación en Ecología y Biogeografía, Universidad de Pamplona, Barrio El Buque, Pamplona, Colombia
| | | | - Tamilie Carvalho
- Laboratório de História Natural de Anfíbios Brasileiros, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Alessandro Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
| | | | - Matthew C Fisher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Sandra V Flechas
- Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia.,Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Sede Venado de Oro, Bogotá, Colombia
| | - Claire N Foster
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia
| | - Patricia Frías-Álvarez
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society London, Regents Park, London NW1 4RY, UK.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Brian Gratwicke
- Smithsonian National Zoological Park and Conservation Biology Institute, Washington, DC 20008, USA
| | - Juan M Guayasamin
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Investigaciones Biológicas y Ambientales BIOSFERA, Laboratorio de Biología Evolutiva, Campus Cumbayá, Quito, Ecuador.,Centro de Investigación de la Biodiversidad y Cambio Climático (BioCamb), Ingeniería en Biodiversidad y Cambio Climático, Facultad de Medio Ambiente, Universidad Tecnológica Indoamérica, Calle Machala y Sabanilla, Quito, Ecuador.,Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Mareike Hirschfeld
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin 10115, Germany
| | - Jonathan E Kolby
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia.,Honduras Amphibian Rescue and Conservation Center, Lancetilla Botanical Garden and Research Center, Tela, Honduras.,The Conservation Agency, Jamestown, RI 02835, USA
| | - Tiffany A Kosch
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, VIC 3030, Australia.,AL Rae Centre for Genetics and Breeding, Massey University, Palmerston North 4442, New Zealand
| | - Enrique La Marca
- School of Geography, Faculty of Forestry Engineering and Environmental Sciences, University of Los Andes, Merida, Venezuela
| | - David B Lindenmayer
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia.,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ana V Longo
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Raúl Maneyro
- Laboratorio de Sistemática e Historia Natural de Vertebrados, Facultad de Ciencias, Universidad de la República, CP 11400 Montevideo, Uruguay
| | - Cait A McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Joseph Mendelson
- Zoo Atlanta, Atlanta, GA 30315, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Gabriela Parra-Olea
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, México
| | | | - Mark-Oliver Rödel
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin 10115, Germany
| | - Sean M Rovito
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Guanajuato CP36824, México
| | - Claudio Soto-Azat
- Centro de Investigación para la Sustentabilidad, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 8370251, Chile
| | - Luís Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Ché Weldon
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Steven M Whitfield
- Conservation and Research Department, Zoo Miami, Miami, FL 33177, USA.,School of Earth, Environment, and Society, Florida International University, Miami, FL 33199, USA
| | - Mark Wilkinson
- Department of Life Sciences, Natural History Museum, London SW7 5BD, UK
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Stefano Canessa
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
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20
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Hammond TT, Blackwood PE, Shablin SA, Richards-Zawacki CL. Relationships between glucocorticoids and infection with Batrachochytrium dendrobatidis in three amphibian species. Gen Comp Endocrinol 2020; 285:113269. [PMID: 31493395 DOI: 10.1016/j.ygcen.2019.113269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/20/2019] [Accepted: 09/03/2019] [Indexed: 11/19/2022]
Abstract
It is often hypothesized that organisms exposed to environmental change may experience physiological stress, which could reduce individual quality and make them more susceptible to disease. Amphibians are amongst the most threatened taxa, particularly in the context of disease, but relatively few studies explore links between stress and disease in amphibian species. Here, we use the fungal pathogen Batrachochytrium dendrobatidis (Bd) and amphibians as an example to explore relationships between disease and glucocorticoids (GCs), metabolic hormones that comprise one important component of the stress response. While previous work is limited, it has largely identified positive relationships between GCs and Bd-infection. However, the causality remains unclear and few studies have integrated both baseline (GC release that is related to standard, physiological functioning) and stress-induced (GC release in response to an acute stressor) measures of GCs. Here, we examine salivary corticosterone before and after exposure to a stressor, in both field and captive settings. We present results for Bd-infected and uninfected individuals of three amphibian species with differential susceptibilities to this pathogen (Rana catesbeiana, R. clamitans, and R. sylvatica). We hypothesized that prior to stress, baseline GCs would be higher in Bd-infected animals, particularly in more Bd-susceptible species. We also expected that after exposure to a stressor, stress-induced GCs would be lower in Bd-infected animals. These species exhibited significant interspecific differences in baseline and stress induced corticosterone, though other variables like sex, body size, and day of year were usually not predictive of corticosterone. In contrast to most previous work, we found no relationships between Bd and corticosterone for two species (R. catesbeiana and R. clamitans), and in the least Bd-tolerant species (R. sylvatica) animals exhibited context-dependent differences in relationships between Bd infection and corticosterone: Bd-positive R. sylvatica had significantly lower baseline and stress-induced corticosterone, with this pattern being stronger in the field than in captivity. These results were surprising, as past work in other species has more often found elevated GCs in Bd-positive animals, a pattern that aligns with well-documented relationships between chronically high GCs, reduced individual quality, and immunosuppression. This work highlights the potential relevance of GCs to disease susceptibility in the context of amphibian declines, while underscoring the importance of characterizing these relationships in diverse contexts.
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Affiliation(s)
- Talisin T Hammond
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA; San Diego Zoo Institute for Conservation Research, 15600 San Pasqual Valley Rd., Escondido, CA 92027, USA.
| | - Paradyse E Blackwood
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
| | - Samantha A Shablin
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
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21
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Byrne AQ, Vredenburg VT, Martel A, Pasmans F, Bell RC, Blackburn DC, Bletz MC, Bosch J, Briggs CJ, Brown RM, Catenazzi A, Familiar López M, Figueroa-Valenzuela R, Ghose SL, Jaeger JR, Jani AJ, Jirku M, Knapp RA, Muñoz A, Portik DM, Richards-Zawacki CL, Rockney H, Rovito SM, Stark T, Sulaeman H, Tao NT, Voyles J, Waddle AW, Yuan Z, Rosenblum EB. Cryptic diversity of a widespread global pathogen reveals expanded threats to amphibian conservation. Proc Natl Acad Sci U S A 2019; 116:20382-20387. [PMID: 31548391 PMCID: PMC6789904 DOI: 10.1073/pnas.1908289116] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Biodiversity loss is one major outcome of human-mediated ecosystem disturbance. One way that humans have triggered wildlife declines is by transporting disease-causing agents to remote areas of the world. Amphibians have been hit particularly hard by disease due in part to a globally distributed pathogenic chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Prior research has revealed important insights into the biology and distribution of Bd; however, there are still many outstanding questions in this system. Although we know that there are multiple divergent lineages of Bd that differ in pathogenicity, we know little about how these lineages are distributed around the world and where lineages may be coming into contact. Here, we implement a custom genotyping method for a global set of Bd samples. This method is optimized to amplify and sequence degraded DNA from noninvasive skin swab samples. We describe a divergent lineage of Bd, which we call BdASIA3, that appears to be widespread in Southeast Asia. This lineage co-occurs with the global panzootic lineage (BdGPL) in multiple localities. Additionally, we shed light on the global distribution of BdGPL and highlight the expanded range of another lineage, BdCAPE. Finally, we argue that more monitoring needs to take place where Bd lineages are coming into contact and where we know little about Bd lineage diversity. Monitoring need not use expensive or difficult field techniques but can use archived swab samples to further explore the history-and predict the future impacts-of this devastating pathogen.
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Affiliation(s)
- Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720
| | - Vance T Vredenburg
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Ghent University, 9820 Merelbeke, Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Ghent University, 9820 Merelbeke, Belgium
| | - Rayna C Bell
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington DC 20560
- Department of Herpetology, California Academy of Sciences, San Francisco, CA 94118
| | - David C Blackburn
- Florida Museum of Natural History, University of Florida, Gainesville, FL 32601
| | - Molly C Bletz
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Cientificas (CSIC), 28006 Madrid, Spain
- Research Unit of Biodiversity, CSIC-Universidad de Oviedo-Gobierno del Principado de Asturias, E-33600 Mieres, Spain
| | - Cheryl J Briggs
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106
| | - Rafe M Brown
- University of Kansas Biodiversity Institute, University of Kansas, Lawrence, KS 66045
- Department of Ecology and Evolution, University of Kansas, Lawrence, KS 66045
| | - Alessandro Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL 33199
| | - Mariel Familiar López
- School of Environment and Sciences, Griffith University, Gold Coast, QLD 4215, Australia
| | | | - Sonia L Ghose
- Department of Evolution and Ecology, University of California, Davis, CA 95616
| | - Jef R Jaeger
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154
| | - Andrea J Jani
- Department of Oceanography, University of Hawai'i at Manoa, Honolulu, HI 96822
| | - Miloslav Jirku
- Institute of Parasitology, Czech Academy of Sciences, 370 05 Ceske Budejovice, Czech Republic
| | - Roland A Knapp
- Sierra Nevada Aquatic Research Laboratory, University of California, Mammoth Lakes, CA 93546
| | - Antonio Muñoz
- Department of Biodiversity Conservation, El Colegio de la Frontera Sur, San Cristobal de las Casas, Chiapas 29290, México
| | - Daniel M Portik
- Department of Ecology and Evolution, University of Arizona, Tucson, AZ 85721
| | | | - Heidi Rockney
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, OR 97331
| | - Sean M Rovito
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Guanajuato CP36824, México
| | - Tariq Stark
- Reptile, Amphibian and Fish Conservation, 6525 ED Nijmegen, The Netherlands
| | - Hasan Sulaeman
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Nguyen Thien Tao
- Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV 89557
| | - Anthony W Waddle
- School of Life Sciences, University of Nevada, Las Vegas, NV 89154
- One Health Research Group, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Zhiyong Yuan
- College of Forestry, Southwest Forestry University, Kunming 650224, Yunnan, China
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720;
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720
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22
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Yang Y, Servedio MR, Richards-Zawacki CL. Imprinting sets the stage for speciation. Nature 2019; 574:99-102. [DOI: 10.1038/s41586-019-1599-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 08/26/2019] [Indexed: 11/09/2022]
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23
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Scheele BC, Pasmans F, Skerratt LF, Berger L, Martel A, Beukema W, Acevedo AA, Burrowes PA, Carvalho T, Catenazzi A, De la Riva I, Fisher MC, Flechas SV, Foster CN, Frías-Álvarez P, Garner TWJ, Gratwicke B, Guayasamin JM, Hirschfeld M, Kolby JE, Kosch TA, La Marca E, Lindenmayer DB, Lips KR, Longo AV, Maneyro R, McDonald CA, Mendelson J, Palacios-Rodriguez P, Parra-Olea G, Richards-Zawacki CL, Rödel MO, Rovito SM, Soto-Azat C, Toledo LF, Voyles J, Weldon C, Whitfield SM, Wilkinson M, Zamudio KR, Canessa S. Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity. Science 2019; 363:1459-1463. [PMID: 30923224 DOI: 10.1126/science.aav0379] [Citation(s) in RCA: 531] [Impact Index Per Article: 106.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/06/2019] [Indexed: 12/18/2022]
Abstract
Anthropogenic trade and development have broken down dispersal barriers, facilitating the spread of diseases that threaten Earth's biodiversity. We present a global, quantitative assessment of the amphibian chytridiomycosis panzootic, one of the most impactful examples of disease spread, and demonstrate its role in the decline of at least 501 amphibian species over the past half-century, including 90 presumed extinctions. The effects of chytridiomycosis have been greatest in large-bodied, range-restricted anurans in wet climates in the Americas and Australia. Declines peaked in the 1980s, and only 12% of declined species show signs of recovery, whereas 39% are experiencing ongoing decline. There is risk of further chytridiomycosis outbreaks in new areas. The chytridiomycosis panzootic represents the greatest recorded loss of biodiversity attributable to a disease.
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Affiliation(s)
- Ben C Scheele
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia. .,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia.,One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Frank Pasmans
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Lee F Skerratt
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Lee Berger
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - An Martel
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Wouter Beukema
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Aldemar A Acevedo
- Programa de Doctorado en Ciencias Biológicas, Laboratorio de Biología Evolutiva, Pontificia Universidad Católica de Chile, Avenida Libertador Bernardo O'Higgins 340, Santiago, Chile.,Grupo de Investigación en Ecología y Biogeografía, Universidad de Pamplona, Barrio El Buque, Km 1, Vía a Bucaramanga, Pamplona, Colombia
| | - Patricia A Burrowes
- Department of Biology, University of Puerto Rico, P.O. Box 23360, San Juan, Puerto Rico
| | - Tamilie Carvalho
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Alessandro Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
| | - Ignacio De la Riva
- Museo Nacional de Ciencias Naturales-CSIC, C/ José Gutiérrez Abascal 2, Madrid 28006, Spain
| | - Matthew C Fisher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Sandra V Flechas
- Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia.,Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Sede Venado de Oro, Paseo Bolívar 16-20, Bogotá, Colombia
| | - Claire N Foster
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia
| | - Patricia Frías-Álvarez
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society London, Regents Park, London NW1 4RY, UK.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Brian Gratwicke
- Smithsonian National Zoological Park and Conservation Biology Institute, Washington, DC 20008, USA
| | - Juan M Guayasamin
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Investigaciones Biológicas y Ambientales BIOSFERA, Laboratorio de Biología Evolutiva, Campus Cumbayá, Quito, Ecuador.,Centro de Investigación de la Biodiversidad y Cambio Climático (BioCamb), Ingeniería en Biodiversidad y Cambio Climático, Facultad de Medio Ambiente, Universidad Tecnológica Indoamérica, Calle Machala y Sabanilla, Quito, Ecuador.,Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Mareike Hirschfeld
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, Berlin 10115, Germany
| | - Jonathan E Kolby
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia.,Honduras Amphibian Rescue and Conservation Center, Lancetilla Botanical Garden and Research Center, Tela, Honduras.,The Conservation Agency, Jamestown, RI 02835, USA
| | - Tiffany A Kosch
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia.,AL Rae Centre for Genetics and Breeding, Massey University, Palmerston North 4442, New Zealand
| | - Enrique La Marca
- School of Geography, Faculty of Forestry Engineering and Environmental Sciences, University of Los Andes, Merida, Venezuela
| | - David B Lindenmayer
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia.,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ana V Longo
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Raúl Maneyro
- Laboratorio de Sistemática e Historia Natural de Vertebrados. Facultad de Ciencias, Universidad de la República. Igua 4225, CP 11400, Montevideo, Uruguay
| | - Cait A McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Joseph Mendelson
- Zoo Atlanta, Atlanta, GA 30315, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Gabriela Parra-Olea
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, México
| | | | - Mark-Oliver Rödel
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, Berlin 10115, Germany
| | - Sean M Rovito
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km 9.6 Libramiento Norte Carretera Irapuato-León, Irapuato, Guanajuato CP36824, México
| | - Claudio Soto-Azat
- Centro de Investigación para la Sustentabilidad, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 8370251, Chile
| | - Luís Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Ché Weldon
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Steven M Whitfield
- Zoo Miami, Conservation and Research Department, Miami, FL 33177, USA.,Florida International University School of Earth, Environment, and Society, 11200 SW 8th St., Miami, FL 33199, USA
| | - Mark Wilkinson
- Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Stefano Canessa
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
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24
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Rogers RL, Zhou L, Chu C, Márquez R, Corl A, Linderoth T, Freeborn L, MacManes MD, Xiong Z, Zheng J, Guo C, Xun X, Kronforst MR, Summers K, Wu Y, Yang H, Richards-Zawacki CL, Zhang G, Nielsen R. Genomic Takeover by Transposable Elements in the Strawberry Poison Frog. Mol Biol Evol 2019; 35:2913-2927. [PMID: 30517748 PMCID: PMC6278860 DOI: 10.1093/molbev/msy185] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We sequenced the genome of the strawberry poison frog, Oophaga pumilio, at a depth of 127.5× using variable insert size libraries. The total genome size is estimated to be 6.76 Gb, of which 4.76 Gb are from high copy number repetitive elements with low differentiation across copies. These repeats encompass DNA transposons, RNA transposons, and LTR retrotransposons, including at least 0.4 and 1.0 Gb of Mariner/Tc1 and Gypsy elements, respectively. Expression data indicate high levels of gypsy and Mariner/Tc1 expression in ova of O. pumilio compared with Xenopus laevis. We further observe phylogenetic evidence for horizontal transfer (HT) of Mariner elements, possibly between fish and frogs. The elements affected by HT are present in high copy number and are highly expressed, suggesting ongoing proliferation after HT. Our results suggest that the large amphibian genome sizes, at least partially, can be explained by a process of repeated invasion of new transposable elements that are not yet suppressed in the germline. We also find changes in the spliceosome that we hypothesize are related to permissiveness of O. pumilio to increases in intron length due to transposon proliferation. Finally, we identify the complement of ion channels in the first genomic sequenced poison frog and discuss its relation to the evolution of autoresistance to toxins sequestered in the skin.
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Affiliation(s)
- Rebekah L Rogers
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, NC
| | - Long Zhou
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,China National Genebank, BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Chong Chu
- Harvard Medical School, Harvard University, Cambridge, MA
| | - Roberto Márquez
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
| | - Ammon Corl
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
| | - Tyler Linderoth
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
| | - Layla Freeborn
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Matthew D MacManes
- Department of Molecular Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH.,Hubbard Center for Genomic Studies, University of New Hampshire, Durham, NH
| | - Zijun Xiong
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Jiao Zheng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Chunxue Guo
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Xu Xun
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | | | - Kyle Summers
- Department of Biology, Eastern Carolina University, Greenville, NC
| | - Yufeng Wu
- Department of Computer Science, University of Connecticut, Storrs, CT
| | - Huanming Yang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,James D. Watson Institute of Genome Sciences, Hangzhou, China
| | | | - Guojie Zhang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,China National Genebank, BGI-Shenzhen, Shenzhen, Guangdong, China.,Department of Biology, Centre for Social Evolution, Universitetsparken 15, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Nielsen
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA
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25
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Saporito RA, Russell MW, Richards-Zawacki CL, Dugas MB. Experimental evidence for maternal provisioning of alkaloid defenses in a dendrobatid frog. Toxicon 2019; 161:40-43. [PMID: 30790578 DOI: 10.1016/j.toxicon.2019.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/23/2019] [Accepted: 02/07/2019] [Indexed: 01/19/2023]
Abstract
Dendrobatid frogs sequester alkaloid defenses from dietary arthropods. Here, we provide experimental evidence that mother strawberry poison frogs (Oophaga pumilio) provision alkaloids to tadpoles. Captive-raised females were fed the synthetic alkaloid decahydroquinoline (DHQ), which we subsequently quantified in their skin, eggs, and developing tadpoles. DHQ quantity was positively associated with tadpole mass/development, suggesting high sequestration rates by tadpoles. These data confirm that tadpoles obtain nutrition and alkaloids by feeding exclusively on maternally provisioned eggs.
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Affiliation(s)
- Ralph A Saporito
- Department of Biology, John Carroll University, 1 John Carroll Boulevard, University Heights, Ohio 44118, USA.
| | - Matthew W Russell
- Department of Biology, John Carroll University, 1 John Carroll Boulevard, University Heights, Ohio 44118, USA
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Building, New Orleans, LA 70118, USA
| | - Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Building, New Orleans, LA 70118, USA; School of Biological Sciences, Illinois State University, Normal, IL, 61790, USA
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26
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Yang Y, Blomenkamp S, Dugas MB, Richards-Zawacki CL, Pröhl H. Mate Choice versus Mate Preference: Inferences about Color-Assortative Mating Differ between Field and Lab Assays of Poison Frog Behavior. Am Nat 2019; 193:598-607. [PMID: 30912970 DOI: 10.1086/702249] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Codivergence of mating traits and mate preferences can lead to behavioral isolation among lineages in early stages of speciation. However, mate preferences limit gene flow only when expressed as mate choice, and numerous factors might be more important than preferences in nature. In the extremely color polytypic strawberry poison frog (Oophaga pumilio), female mate preferences have codiverged with color in most allopatric populations tested. Whether these lab-assayed preferences predict mating (gene flow) in the wild remains unclear. We observed courting pairs in a natural contact zone between red and blue lineages until oviposition or courtship termination. We found color-assortative mating in a disturbed habitat with high population density but not in a secondary forest with lower density. Our results suggest color-assortative O. pumilio mate choice in the wild but also mating patterns that do not match those predicted by lab-assayed preferences.
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27
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Robak MJ, Reinert LK, Rollins-Smith LA, Richards-Zawacki CL. Out in the cold and sick: Low temperatures and fungal infections impair a frog's skin defenses. J Exp Biol 2019; 222:jeb.209445. [DOI: 10.1242/jeb.209445] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 09/02/2019] [Indexed: 12/29/2022]
Abstract
Amphibians worldwide continue to battle an emerging infectious disease, chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd). Southern leopard frogs, Rana sphenocephala, are known to become infected with this pathogen, yet they are considered ‘of least concern’ for declines due to chytridiomycosis. Previous studies have shown that R. sphenocephala secretes four antimicrobial peptides (AMPs) onto their skin which may play an important role in limiting susceptibility to chytridiomycosis. Here we examined the (1) effects of temperature and AMP depletion on infections with Bd and (2) effects of temperature and Bd infection on the capacity to secrete AMPs in juvenile leopard frogs. Pathogen burden and mortality were greater in frogs exposed to Bd at low temperature but did not increase following monthly AMP depletion. Both low temperature and Bd exposure reduced the capacity of juvenile frogs to restore peptides after monthly depletions. Frogs held at 14°C were poorly able to restore peptides in comparison with those at 26 °C. Frogs held at 26 °C were better able to restore their peptides, but when exposed to Bd, this capacity was significantly reduced. These results strongly support the hypothesis that both colder temperatures and Bd infections impair the capacity of juvenile frogs to produce and secrete AMPs, an important component of their innate defense against chytrid fungi and other pathogens. Thus, in the face of unpredictable climate changes and enzootic pathogens, assessments of disease risk should consider the potential for effects of environmental variation and pathogen exposure on the quality of host defenses.
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Affiliation(s)
- Matthew J. Robak
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
| | - Laura K. Reinert
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Louise A. Rollins-Smith
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Corinne L. Richards-Zawacki
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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28
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Sauer EL, Fuller RC, Richards-Zawacki CL, Sonn J, Sperry JH, Rohr JR. Correction to 'Variation in individual temperature preferences, not behavioural fever, affects susceptibility to chytridiomycosis in amphibians'. Proc Biol Sci 2018; 285:rspb.2018.2466. [PMID: 30464070 DOI: 10.1098/rspb.2018.2466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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29
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Rosencrans RF, Leslie CE, Perkins KA, Walkowski W, Gordon WC, Richards-Zawacki CL, Bazan NG, Farris HE. Quantifying the relationship between optical anatomy and retinal physiological sensitivity: A comparative approach. J Comp Neurol 2018; 526:3045-3057. [PMID: 30198557 PMCID: PMC10075234 DOI: 10.1002/cne.24531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 07/27/2018] [Accepted: 08/27/2018] [Indexed: 02/03/2023]
Abstract
Light intensity varies 1 million-fold between night and day, driving the evolution of eye morphology and retinal physiology. Despite extensive research across taxa showing anatomical adaptations to light niches, surprisingly few empirical studies have quantified the relationship between such traits and the physiological sensitivity to light. In this study, we employ a comparative approach in frogs to determine the physiological sensitivity of eyes in two nocturnal (Rana pipiens, Hyla cinerea) and two diurnal species (Oophaga pumilio, Mantella viridis), examining whether differences in retinal thresholds can be explained by ocular and cellular anatomy. Scotopic electroretinogram (ERG) analysis of relative b-wave amplitude reveals 10- to 100-fold greater light sensitivity in nocturnal compared to diurnal frogs. Ocular and cellular optics (aperture, focal length, and rod outer segment dimensions) were assessed via the Land equation to quantify differences in optical sensitivity. Variance in retinal thresholds was overwhelmingly explained by Land equation solutions, which describe the optical sensitivity of single rods. Thus, at the b-wave, stimulus-response thresholds may be unaffected by photoreceptor convergence (which create larger, combined collecting areas). Follow-up experiments were conducted using photopic ERGs, which reflect cone vision. Under these conditions, the relative difference in thresholds was reversed, such that diurnal species were more sensitive than nocturnal species. Thus, photopic data suggest that rod-specific adaptations, not ocular anatomy (e.g., aperture and focal distance), drive scotopic thresholds differences. To the best of our knowledge, these data provide the first quantified relationship between optical and physiological sensitivity in vertebrates active in different light regimes.
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Affiliation(s)
- Robert F Rosencrans
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana
| | - Caitlin E Leslie
- Department of Integrative Biology, University of Texas, Austin, Texas
| | - Keith A Perkins
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana
| | - Whitney Walkowski
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana
| | - William C Gordon
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana.,Department of Ophthalmology, Louisiana State University School of Medicine, New Orleans, Louisiana
| | | | - Nicolas G Bazan
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana.,Department of Ophthalmology, Louisiana State University School of Medicine, New Orleans, Louisiana
| | - Hamilton E Farris
- Neuroscience Center, Louisiana State University School of Medicine, New Orleans, Louisiana.,Department of Otorhinolaryngology, Louisiana State University School of Medicine, New Orleans, Louisiana.,Department of Cell Biology and Anatomy, Louisiana State University School of Medicine, New Orleans, Louisiana
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30
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Hammond TT, Au ZA, Hartman AC, Richards-Zawacki CL. Assay validation and interspecific comparison of salivary glucocorticoids in three amphibian species. Conserv Physiol 2018; 6:coy055. [PMID: 30279992 PMCID: PMC6158758 DOI: 10.1093/conphys/coy055] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 08/30/2018] [Accepted: 09/04/2018] [Indexed: 05/23/2023]
Abstract
Amphibians are one of the most threatened groups of species, facing stressors ranging from habitat degradation and pollution to disease and overexploitation. Stress hormones (glucocorticoids, GCs) provide one quantitative metric of stress, and developing non-invasive methods for measuring GCs in amphibians would clarify how diverse environmental stressors impact individual health in this taxonomic group. Saliva is an advantageous matrix for quantifying GCs, as it is sampled less invasively than plasma while still detecting both baseline and acute elevation of GCs within a short timeframe. Little work has employed this method in amphibian species, and it has never been pharmacologically and biologically validated. Here, we conduct analytical, pharmacological and biological validation experiments for measuring salivary corticosterone in three amphibian species: the American bullfrog (Rana catesbeiana), the green frog (Rana clamitans) and the northern leopard frog (Rana pipiens). These species are faced with a broad range of environmental challenges, and in part of its range R. pipiens populations are currently in decline. In addition to demonstrating that this method can be reliably used in multiple amphibian species, we present an examination of intrinsic biological factors (sex, body condition) that may contribute to GC secretion, and a demonstration that saliva can be collected from free-living animals in the field to quantify corticosterone. Our findings suggest that saliva may be useful for less invasively quantifying GCs in many amphibian species.
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Affiliation(s)
- Talisin T Hammond
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave. at Ruskin Ave., Pittsburgh, PA, USA
| | - Zoe A Au
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave. at Ruskin Ave., Pittsburgh, PA, USA
| | - Allison C Hartman
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave. at Ruskin Ave., Pittsburgh, PA, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave. at Ruskin Ave., Pittsburgh, PA, USA
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31
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Brannelly LA, Chatfield MWH, Sonn J, Robak M, Richards-Zawacki CL. Fungal infection has sublethal effects in a lowland subtropical amphibian population. BMC Ecol 2018; 18:34. [PMID: 30217158 PMCID: PMC6137908 DOI: 10.1186/s12898-018-0189-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 09/03/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been implicated as a primary cause of decline in many species around the globe. However, there are some species and populations that are known to become infected in the wild, yet declines have not been observed. Here we conducted a yearlong capture-mark-recapture study and a 2-year long disease monitoring study of northern cricket frogs, Acris crepitans, in the lowland subtropical forests of Louisiana. RESULTS We found little evidence for an impact of Bd infection on survival; however, Bd infection did appear to cause sublethal effects, including increased capture probability in the field. CONCLUSIONS Our study suggests that even in apparently stable populations, where Bd does not appear to cause mortality, there may be sublethal effects of infection that can impact a host population's dynamics and structure. Understanding and documenting such sublethal effects of infection on wild, seemingly stable populations is important, particularly for predicting future population declines.
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Affiliation(s)
- Laura A Brannelly
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
| | | | - Julia Sonn
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
| | - Matthew Robak
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
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32
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Sauer EL, Fuller RC, Richards-Zawacki CL, Sonn J, Sperry JH, Rohr JR. Variation in individual temperature preferences, not behavioural fever, affects susceptibility to chytridiomycosis in amphibians. Proc Biol Sci 2018; 285:rspb.2018.1111. [PMID: 30135162 DOI: 10.1098/rspb.2018.1111] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/27/2018] [Indexed: 11/12/2022] Open
Abstract
The ability of wildlife populations to mount rapid responses to novel pathogens will be critical for mitigating the impacts of disease outbreaks in a changing climate. Field studies have documented that amphibians preferring warmer temperatures are less likely to be infected with the fungal pathogen Batrachochytrium dendrobatidis (Bd). However, it is unclear whether this phenomenon is driven by behavioural fever or natural variation in thermal preference. Here, we placed frogs in thermal gradients, tested for temperature preferences and measured Bd growth, prevalence, and the survival of infected animals. Although there was significant individual- and species-level variation in temperature preferences, we found no consistent evidence of behavioural fever across five frog species. Interestingly, for species that preferred warmer temperatures, the preferred temperatures of individuals were negatively correlated with Bd growth on hosts, while the opposite correlation was true for species preferring cooler temperatures. Our results suggest that variation in thermal preference, but not behavioural fever, might shape the outcomes of Bd infections for individuals and populations, potentially resulting in selection for individual hosts and host species whose temperature preferences minimize Bd growth and enhance host survival during epidemics.
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Affiliation(s)
- Erin L Sauer
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Rebecca C Fuller
- Department of Animal Biology, University of Illinois, Champaign, IL 61820, USA
| | | | - Julia Sonn
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
| | - Jinelle H Sperry
- US Army Engineer Research and Development Center, Champaign, IL 61826, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
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Voyles J, Woodhams DC, Saenz V, Byrne AQ, Perez R, Rios-Sotelo G, Ryan MJ, Bletz MC, Sobell FA, McLetchie S, Reinert L, Rosenblum EB, Rollins-Smith LA, Ibáñez R, Ray JM, Griffith EJ, Ross H, Richards-Zawacki CL. Shifts in disease dynamics in a tropical amphibian assemblage are not due to pathogen attenuation. Science 2018; 359:1517-1519. [PMID: 29599242 DOI: 10.1126/science.aao4806] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 03/01/2018] [Indexed: 11/02/2022]
Abstract
Infectious diseases rarely end in extinction. Yet the mechanisms that explain how epidemics subside are difficult to pinpoint. We investigated host-pathogen interactions after the emergence of a lethal fungal pathogen in a tropical amphibian assemblage. Some amphibian host species are recovering, but the pathogen is still present and is as pathogenic today as it was almost a decade ago. In addition, some species have defenses that are more effective now than they were before the epidemic. These results suggest that host recoveries are not caused by pathogen attenuation and may be due to shifts in host responses. Our findings provide insights into the mechanisms underlying disease transitions, which are increasingly important to understand in an era of emerging infectious diseases and unprecedented global pandemics.
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Affiliation(s)
- Jamie Voyles
- Department of Biology, University of Nevada, Reno, Reno, NV, USA.
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts-Boston, Boston, MA, USA.,Smithsonian Tropical Research Institute, Ancón, Panamá
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, USA
| | - Rachel Perez
- Department of Biology, New Mexico Institute of Mining and Technology, Socorro, NM, USA
| | | | - Mason J Ryan
- Department of Biology, University of Nevada, Reno, Reno, NV, USA.,Arizona Game and Fish Department, Phoenix, AZ, USA
| | - Molly C Bletz
- Department of Biology, University of Massachusetts-Boston, Boston, MA, USA
| | - Florence Ann Sobell
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Shawna McLetchie
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Laura Reinert
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, USA
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Roberto Ibáñez
- Smithsonian Tropical Research Institute, Ancón, Panamá.,Sistema Nacional de Investigación, Panamá, Panamá
| | | | | | - Heidi Ross
- Smithsonian Tropical Research Institute, Ancón, Panamá
| | - Corinne L Richards-Zawacki
- Smithsonian Tropical Research Institute, Ancón, Panamá.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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34
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Robak MJ, Richards-Zawacki CL. Temperature-Dependent Effects of Cutaneous Bacteria on a Frog's Tolerance of Fungal Infection. Front Microbiol 2018; 9:410. [PMID: 29563909 PMCID: PMC5845872 DOI: 10.3389/fmicb.2018.00410] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/21/2018] [Indexed: 11/27/2022] Open
Abstract
Defense against pathogens is one of many benefits that bacteria provide to animal hosts. A clearer understanding of how changes in the environment affect the interactions between animals and their microbial benefactors is needed in order to predict the impact and dynamics of emerging animal diseases. Due to its dramatic effects on the physiology of animals and their pathogens, temperature may be a key variable modulating the level of protection that beneficial bacteria provide to their animal hosts. Here we investigate how temperature and the makeup of the skin microbial community affect the susceptibility of amphibian hosts to infection by Batrachochytrium dendrobatidis (Bd), one of two fungal pathogens known to cause the disease chytridiomycosis. To do this, we manipulated the skin bacterial communities of susceptible hosts, northern cricket frogs (Acris crepitans), prior to exposing these animals to Bd under two different ecologically relevant temperatures. Our manipulations included one treatment where antibiotics were used to reduce the skin bacterial community, one where the bacterial community was augmented with the antifungal bacterium, Stenotrophomonas maltophilia, and one in which the frog’s skin bacterial community was left intact. We predicted that frogs with reduced skin bacterial communities would be more susceptible (i.e., less resistant to and/or tolerant of Bd infection), and frogs with skin bacterial communities augmented with the known antifungal bacterium would be less susceptible to Bd infection and chytridiomycosis. However, we also predicted that this interaction would be temperature dependent. We found a strong effect of temperature but not of skin microbial treatment on the probability and intensity of infection in Bd-exposed frogs. Whether temperature affected survival; however, it differed among our skin microbial treatment groups, with animals having more S. maltophilia on their skin surviving longer at 14 but not at 26°C. Our results suggest that temperature was the predominant factor influencing Bd’s ability to colonize the host (i.e., resistance) but that the composition of the cutaneous bacterial community was important in modulating the host’s ability to survive (i.e., tolerate) a heavy Bd infection.
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Affiliation(s)
- Matthew J Robak
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, United States
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, United States.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
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35
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Yang Y, Dugas MB, Sudekum HJ, Murphy SN, Richards-Zawacki CL. Male-male aggression is unlikely to stabilize a poison frog polymorphism. J Evol Biol 2018; 31:457-468. [PMID: 29345026 DOI: 10.1111/jeb.13243] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/18/2017] [Accepted: 01/09/2018] [Indexed: 12/13/2022]
Abstract
Phenotypic polymorphism is common in animals, and the maintenance of multiple phenotypes in a population requires forces that act against homogenizing drift and selection. Male-male competition can contribute to the stability of a polymorphism when males compete primarily with males of the same phenotype. In and around a contact zone between red and blue lineages of the poison frog Oophaga pumilio, we used simulated territorial intrusions to test the nonexclusive predictions that males would direct more aggression towards males of (i) their own phenotype and/or (ii) the phenotype that is most common in their population. Males in the monomorphic red and blue populations that flank the contact zone were more aggressive towards simulated intruders that matched the local coloration. However, males in the two polymorphic populations biased aggression towards neither their own colour nor the colour most common in their population. In sympatry, the rarer colour morph gains no advantage via reduced male-male aggression from territorial males in these O. pumilio populations, and so male aggression seems unlikely to stabilize colour polymorphism on its own. More broadly, these results suggest that the potential for divergent male aggression biases to maintain phenotypic diversity depends on the mechanism(s) that generate the biases and the degree to which these mechanisms persist in sympatry.
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Affiliation(s)
- Y Yang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - M B Dugas
- Watershed Studies Institute and Department of Biological Sciences, Murray State University, Murray, KY, USA
| | - H J Sudekum
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
| | - S N Murphy
- Smithsonian Tropical Research Institute, Balboa, Ancon, República de Panamá
| | - C L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.,Smithsonian Tropical Research Institute, Balboa, Ancon, República de Panamá
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36
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Sonn JM, Berman S, Richards-Zawacki CL. The Influence of Temperature on Chytridiomycosis In Vivo. Ecohealth 2017; 14:762-770. [PMID: 28879516 DOI: 10.1007/s10393-017-1269-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 06/23/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
Chytridiomycosis, an amphibian disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an ideal system for studying the influence of temperature on host-pathogen relationships because both host and pathogen are ectothermic. Studies of Bd in culture suggest that optimal growth occurs between 17 and 23°C, and death of the fungus occurs above 29 or below 0°C. Amphibian immune systems, however, are also temperature dependent and often more effective at higher temperatures. We therefore hypothesized that pathogen load, probability of infection and mortality in Bd-exposed frogs would peak at a lower temperature than that at which Bd grows best in vitro. To test this, we conducted a study where Bd- and sham-exposed Northern cricket frogs (Acris crepitans) were incubated at six temperatures between 11 and 26°C. While probability of infection did not differ across temperatures, pathogen load and mortality were inversely related to temperature. Survival of infected hosts was greatest between 20 and 26°C, temperatures where Bd grows well in culture. These results demonstrate that the conditions under which a pathogen grows best in culture do not necessarily reflect patterns of pathogenicity, an important consideration for predicting the threat of this and other wildlife pathogens.
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Affiliation(s)
- Julia M Sonn
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Bldg., New Orleans, LA, 70118, USA.
| | - Scott Berman
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Bldg., New Orleans, LA, 70118, USA
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, 400 Lindy Boggs Bldg., New Orleans, LA, 70118, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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37
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Yang Y, Richards-Zawacki CL, Devar A, Dugas MB. Poison frog color morphs express assortative mate preferences in allopatry but not sympatry. Evolution 2016; 70:2778-2788. [PMID: 27704539 DOI: 10.1111/evo.13079] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 09/12/2016] [Accepted: 09/20/2016] [Indexed: 11/29/2022]
Abstract
The concurrent divergence of mating traits and preferences is necessary for the evolution of reproductive isolation via sexual selection, and such coevolution has been demonstrated in diverse lineages. However, the extent to which assortative mate preferences are sufficient to drive reproductive isolation in nature is less clear. Natural contact zones between lineages divergent in traits and preferences provide exceptional opportunities for testing the predicted evolutionary consequences of such divergence. The strawberry poison frog (Oophaga pumilio) displays extreme color polymorphism in and around the young Bocas del Toro archipelago. In a transition zone between red and blue allopatric lineages, we asked whether female preferences diverged along with coloration, and whether any divergent preferences persist in a zone of sympatry. When choosing among red, blue and phenotypically intermediate males, females from monomorphic red and monomorphic blue populations both expressed assortative preferences. However, red, blue, and intermediate females from the contact zone all preferred red males, suggesting that divergent preferences may be insufficient to effect behavioral isolation. Our results highlight the complexity of behavioral isolation, and the need for studies that can reveal the circumstances under which divergent preferences do and do not contribute to speciation.
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Affiliation(s)
- Yusan Yang
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.,Current Address: Department of Biological Sciences, University of Pittsburgh, 2429 Fifth Ave, Pittsburgh, Pennsylvania, 15260
| | - Corinne L Richards-Zawacki
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260.,Smithsonian Tropical Research Institute, Balboa, Ancon, Republica de Panama
| | - Anisha Devar
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, 70118
| | - Matthew B Dugas
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, 44106
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38
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Dugas MB, Wamelink CN, Killius AM, Richards-Zawacki CL. Parental care is beneficial for offspring, costly for mothers, and limited by family size in an egg-feeding frog. Behav Ecol 2015. [DOI: 10.1093/beheco/arv173] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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39
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Dugas MB, Moore MP, Wamelink CN, Richards-Zawacki CL, Martin RA. An experimental test for age-related improvements in reproductive performance in a frog that cares for its young. Naturwissenschaften 2015; 102:48. [PMID: 26286323 DOI: 10.1007/s00114-015-1302-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/06/2015] [Accepted: 08/09/2015] [Indexed: 11/24/2022]
Abstract
Reproductive performance often increases with age in long-lived iteroparous organisms, a pattern that can result from within-individual increases in effort and/or competence. In free-living populations, it is typically difficult to distinguish these mechanisms or to isolate particular features of reproduction-influencing outcomes. In captive Oophaga pumilio, a frog in which mothers provide extended offspring provisioning via trophic eggs, we experimentally manipulated the age at which females started breeding and then monitored them across repeated reproductive events. This experiment allowed us to decouple age and experience and isolate maternal care as the proximate source of any differences in performance. Younger first-time mothers produced larger broods than older first-time mothers, but did not rear more offspring to independence. Across repeated reproductive events, maternal age was unassociated with any metric of performance. At later reproductive events, however, mothers produced fewer metamorphs, and a lower proportion of individuals in their broods reached independence. These patterns suggest that performance does not improve with age or breeding experience in this frog, and that eventual declines in performance are driven by reproductive activity, not age per se. Broadly, age-specific patterns of reproductive performance may depend on the proximate mechanism by which parents influence offspring fitness and how sensitive these are to effort and competence.
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Affiliation(s)
- Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA,
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40
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McCaffery R, Richards-Zawacki CL, Lips KR. The demography of Atelopus decline: Harlequin frog survival and abundance in central Panama prior to and during a disease outbreak. Glob Ecol Conserv 2015. [DOI: 10.1016/j.gecco.2015.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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41
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Dugas MB, Halbrook SR, Killius AM, del Sol JF, Richards-Zawacki CL. Colour and Escape Behaviour in Polymorphic Populations of an Aposematic Poison Frog. Ethology 2015. [DOI: 10.1111/eth.12396] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew B. Dugas
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
| | - Susannah R. Halbrook
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
| | - Allison M. Killius
- Department of Ecology and Evolutionary Biology; Tulane University; New Orleans LA USA
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42
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Dugas MB, Richards-Zawacki CL. A captive breeding experiment reveals no evidence of reproductive isolation among lineages of a polytypic poison frog. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12571] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew B. Dugas
- Department of Ecology and Evolutionary Biology; Tulane University; 400 Lindy Boggs Building New Orleans LA 70118 USA
| | - Corinne L. Richards-Zawacki
- Department of Ecology and Evolutionary Biology; Tulane University; 400 Lindy Boggs Building New Orleans LA 70118 USA
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43
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Brannelly LA, McMahon TA, Hinton M, Lenger D, Richards-Zawacki CL. Batrachochytrium dendrobatidis in natural and farmed Louisiana crayfish populations: prevalence and implications. Dis Aquat Organ 2015; 112:229-235. [PMID: 25590773 DOI: 10.3354/dao02817] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) has been linked to global declines and extinctions of amphibians, making it one of the most devastating wildlife pathogens known. Understanding the factors that affect disease dynamics in this system is critical for mitigating infection and protecting threatened species. Crayfish are hosts of this pathogen and can transmit Bd to amphibians. Because they co-occur with susceptible amphibian communities, crayfish may be important alternative hosts for Bd. Understanding the prevalence and seasonal dynamics of crayfish infections is of agricultural and ecological interest in areas where crayfish are farmed and traded for human consumption. We conducted a survey of Bd in farmed and natural crayfish (Procambarus spp.) populations in Louisiana, USA. We found that Bd prevalence and infection intensity was low in both farmed and native populations and that prevalence varied seasonally in wild Louisiana crayfish. This seasonal pattern mirrors that seen in local amphibians. As crayfish are an important globally traded freshwater taxon, even with low prevalence, they could be an important vector in the spread of Bd.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, College of Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
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Dugas MB, Yeager J, Richards-Zawacki CL. Carotenoid supplementation enhances reproductive success in captive strawberry poison frogs (Oophaga pumilio). Zoo Biol 2013; 32:655-8. [PMID: 24151130 DOI: 10.1002/zoo.21102] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/12/2013] [Accepted: 09/20/2013] [Indexed: 11/10/2022]
Abstract
Amphibians are currently experiencing the most severe declines in biodiversity of any vertebrate, and their requirements for successful reproduction are poorly understood. Here, we show that supplementing the diet of prey items (fruit flies) with carotenoids has strong positive effects on the reproduction of captive strawberry poison frogs (Oophaga pumilio), substantially increasing the number of metamorphs produced by pairs. This improved reproduction most likely arose via increases in the quality of both the fertilized eggs from which tadpoles develop and trophic eggs that are fed to tadpoles by mothers. Frogs in this colony had previously been diagnosed with a Vitamin A deficiency, and this supplementation may have resolved this issue. These results support growing evidence of the importance of carotenoids in vertebrate reproduction and highlight the nuanced ways in which nutrition constrains captive populations.
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Affiliation(s)
- Matthew B Dugas
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana
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Chatfield MWH, Brannelly LA, Robak MJ, Freeborn L, Lailvaux SP, Richards-Zawacki CL. Fitness consequences of infection by Batrachochytrium dendrobatidis in northern leopard frogs (Lithobates pipiens). Ecohealth 2013; 10:90-98. [PMID: 23604643 DOI: 10.1007/s10393-013-0833-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 01/18/2013] [Accepted: 03/19/2013] [Indexed: 06/02/2023]
Abstract
The amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been linked to amphibian declines and extinctions worldwide. The pathogen has been found on amphibians throughout eastern North America, but has not been associated with mass die-offs in this region. In this study, we conducted laboratory experiments on the effects of Bd infection in a putative carrier species, Lithobates pipiens, using two estimators of fitness: jumping performance and testes morphology. Over the 8-week study period, peak acceleration during jumping was not significantly different between infected and uninfected animals. Peak velocity, however, was significantly lower for infected animals after 8 weeks. Two measures of sperm production, germinal epithelium depth, and maximum spermatic cyst diameter, showed no difference between infected and uninfected animals. The width, but not length, of testes of infected animals was significantly greater than in uninfected animals. This study is the first to show effects on whole-organism performance of Bd infection in post-metamorphic amphibians, and may have important long-term, evolutionary implications for amphibian populations co-existing with Bd infection.
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Affiliation(s)
- Matthew W H Chatfield
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA.
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Brannelly LA, Richards-Zawacki CL, Pessier AP. Clinical trials with itraconazole as a treatment for chytrid fungal infections in amphibians. Dis Aquat Organ 2012; 101:95-104. [PMID: 23135136 DOI: 10.3354/dao02521] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Due in large part to recent global declines and extinctions, amphibians are the most threatened vertebrate group. Captive assurance colonies may be the only lifeline for some rapidly disappearing species. Maintaining these colonies free of disease represents a challenge to effective amphibian conservation. The fungal disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is one of the major contributors to global amphibian declines and also poses a serious threat to captive assurance colonies. Many treatment options for Bd infection have not been experimentally tested and the commonly administered dosages of some drugs are known to have negative side effects, highlighting a need for clinical trials. The objective of this study was to clinically test the drug itraconazole as a method for curing Bd infection. We bathed Bd-positive juveniles of 2 anuran amphibian species, Litoria caerulea and Incilius nebulifer, in aqueous itraconazole, varying the concentration and duration of treatment, to find the combination that caused the fewest side effects while also reliably ridding animals of Bd. Our results suggest that a bath in 0.0025% itraconazole for 5 min d-1 for 6 d reliably cures Bd infection and causes fewer side effects than the longer treatment times and higher concentrations of this drug that are commonly administered.
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Affiliation(s)
- Laura A Brannelly
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana 70118, USA.
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Chatfield MWH, Moler P, Richards-Zawacki CL. The amphibian chytrid fungus, Batrachochytrium dendrobatidis, in fully aquatic salamanders from Southeastern North America. PLoS One 2012; 7:e44821. [PMID: 22984569 PMCID: PMC3439441 DOI: 10.1371/journal.pone.0044821] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 08/14/2012] [Indexed: 12/01/2022] Open
Abstract
Little is known about the impact that the pathogenic amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has on fully aquatic salamander species of the eastern United States. As a first step in determining the impacts of Bd on these species, we aimed to determine the prevalence of Bd in wild populations of fully aquatic salamanders in the genera Amphiuma, Necturus, Pseudobranchus, and Siren. We sampled a total of 98 salamanders, representing nine species from sites in Florida, Mississippi, and Louisiana. Overall, infection prevalence was found to be 0.34, with significant differences among genera but no clear geographic pattern. We also found evidence for seasonal variation, but additional sampling throughout the year is needed to clarify this pattern. The high rate of infection discovered in this study is consistent with studies of other amphibians from the southeastern United States. Coupled with previously published data on life histories and population densities, the results presented here suggest that fully aquatic salamanders may be serving as important vectors of Bd and the interaction between these species and Bd warrants additional research.
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Affiliation(s)
- Matthew W H Chatfield
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana, United States of America.
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Brannelly LA, Chatfield MWH, Richards-Zawacki CL. Field and laboratory studies of the susceptibility of the green treefrog (Hyla cinerea) to Batrachochytrium dendrobatidis infection. PLoS One 2012; 7:e38473. [PMID: 22685572 PMCID: PMC3369911 DOI: 10.1371/journal.pone.0038473] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/07/2012] [Indexed: 11/18/2022] Open
Abstract
Amphibians worldwide are experiencing devastating declines, some of which are due to the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd). Populations in the southeastern United States, however, have not been noticeably affected by the pathogen. The green treefrog (Hyla cinerea) is abundant and widespread in the southeastern United States, but has not been documented to harbor Bd infection. This study examined the susceptibility of H. cinerea to two strains of Bd in the lab and the prevalence of infection in wild populations of this species in southeastern Louisiana. Although we were able to infect H. cinerea with Bd in the lab, we did not observe any clinical signs of chytridiomycosis. Furthermore, infection by Bd does not appear to negatively affect body condition or growth rate of post-metamorphic individuals. We found no evidence of infection in surveys of wild H. cinerea. Our results suggest that H. cinerea is not susceptible to chytridiomycosis post-metamorphosis and probably is not an important carrier of the fungal pathogen Bd in the southeastern United States, although susceptibility at the larval stage remains unknown.
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Affiliation(s)
- Laura A Brannelly
- Ecology and Evolutionary Biology Department, Tulane University, New Orleans, Louisiana, United States of America.
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Richards-Zawacki CL, Wang IJ, Summers K. Mate choice and the genetic basis for colour variation in a polymorphic dart frog: inferences from a wild pedigree. Mol Ecol 2012; 21:3879-92. [PMID: 22650383 DOI: 10.1111/j.1365-294x.2012.05644.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding how reproductive barriers evolve during speciation remains an important question in evolution. Divergence in mating preferences may be a common first step in this process. The striking colour pattern diversity of strawberry dart frog (Dendrobates pumilio) populations has likely been shaped by sexual selection. Previous laboratory studies have shown that females attend to male coloration and prefer to court with males of their own colour, suggesting that divergent morphs may be reproductively isolated. To test this hypothesis, we used molecular data to estimate pedigree relationships from a polymorphic population. Whereas in the laboratory both red and yellow females preferred to court with males of their own phenotype, our pedigree shows a pattern of assortative mating only for red females. In the wild, yellow females appear to be less choosy about their mates, perhaps because they incur higher costs associated with searching than females of the more common red phenotype. We also used our pedigree to investigate the genetic basis for colour-pattern variation. The phenotype frequencies we observed were consistent with those expected if dorsal background coloration is controlled by a single locus, with complete dominance of red over yellow. Our results not only help clarify the role of sexual selection in reducing gene flow, but also shed light on the mechanisms underlying colour-pattern variation among sympatric colour morphs. The difference we observed between mating preferences measured under laboratory conditions and the pattern of mate choice observed in the wild highlight the importance of field studies for understanding behavioural reproductive isolation.
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Chatfield MWH, Richards-Zawacki CL. Elevated temperature as a treatment for Batrachochytrium dendrobatidis infection in captive frogs. Dis Aquat Organ 2011; 94:235-238. [PMID: 21790070 DOI: 10.3354/dao02337] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian declines worldwide. In vitro laboratory studies and those done on wild populations indicate that Bd grows best at cool temperatures between 17 and 25 degrees C. In the present study, we tested whether moderately elevating the ambient temperature to 30 degrees C could be an effective treatment for frogs infected with Bd. We acquired 35 bullfrogs Rana catesbeiana from breeding facilities and 36 northern cricket frogs Acris crepitans from the wild and acclimated them to either 23 or 26 degrees C for 1 mo. Following the acclimation period, frogs were tested for the presence of Bd using qPCR TaqMan assays. The 12 R. catesbeiana and 16 A. crepitans that tested positive for Bd were subjected to 30 degrees C for 10 consecutive days before returning frogs to their starting temperatures. Post-treatment testing revealed that 27 of the 28 frogs that had tested positive were no longer infected with Bd; only a single A. crepitans remained infected following treatment. This result indicates that elevating ambient temperature to a moderate 30 degrees C can be effective as a treatment for Bd infection in captive amphibians, and suggests that heat may be a superior alternative to antifungal drugs.
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Affiliation(s)
- Matthew W H Chatfield
- Tulane University, Department of Ecology and Evolutionary Biology, New Orleans, Louisiana 70118, USA.
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