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Aguiar O, Sonnega S, DiNuzzo ER, Sheriff MJ. Playing it safe; risk-induced trait responses increase survival in the face of predation. J Anim Ecol 2023; 92:690-697. [PMID: 36597705 DOI: 10.1111/1365-2656.13880] [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] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 12/22/2022] [Indexed: 01/05/2023]
Abstract
Predation risk effects are impacts on prey caused by predators that do not include consumption. These can include changes in prey behaviour, physiology, and morphology (i.e. risk-induced trait responses), which can have consequences to individual fitness and population dynamics (i.e. non-consumptive effects). While these risk-induced trait responses (RITRs) can lower individual fitness as compared to prey not exposed to risk, they are assumed to increase fitness in the presence of predators. While much work has been built upon this assumption, most evidence occurs in consumptive experiments where the trait values of consumed prey are unknown. We have little evidence showing individuals with a greater magnitude of RITR have greater survival. Here, we tested the hypothesis that RITRs increase survival in the presence of predators, but come at a cost to growth. We tested this hypothesis using Nucella lapillus as prey and Carcinus maenas as a predator and including mussels as a basal resource in a two-phase mesocosm experimental set-up. In phase 1, Nucella were placed into either a control or risk treatment (exposure to non-lethal Carcinus) for 28 days and their behaviour and growth measured. In phase 2, a lethal Carcinus was added to all mesocosms (non-lethal crabs were removed), and survival was recorded for 15 days. At the treatment (group) level, we found that Nucella exposed to predation risk in phase 1 had significantly greater risk aversion behaviour (summed score of risky vs. safe behaviour) and significantly lower growth. In phase 2, we found that Nucella exposed to predation risk had greater survival. At the individual level (regardless of treatment), we found that Nucella with greater risk aversion scores in phase 1 had significantly higher survival in phase 2 when exposed to a lethal predator, but this came at a cost to their growth. This study provides some of the first empirical evidence, at both the group and individual level, testing a long-held assumption that predation risk-induced behavioural responses increase survival in the face of direct predation, but that these responses come at a cost to the prey. These results add to our growing understanding of the benefits of RITRs to individual fitness and non-consumptive effects generally.
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Affiliation(s)
- Olivia Aguiar
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
| | - Sam Sonnega
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
| | - Eleanor R DiNuzzo
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
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2
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Peacor SD, Dorn NJ, Smith JA, Peckham NE, Cherry MJ, Sheriff MJ, Kimbro DL. A skewed literature: Few studies evaluate the contribution of predation-risk effects to natural field patterns. Ecol Lett 2022; 25:2048-2061. [PMID: 35925978 PMCID: PMC9545701 DOI: 10.1111/ele.14075] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 06/20/2022] [Indexed: 11/30/2022]
Abstract
A narrative in ecology is that prey modify traits to reduce predation risk, and the trait modification has costs large enough to cause ensuing demographic, trophic and ecosystem consequences, with implications for conservation, management and agriculture. But ecology has a long history of emphasising that quantifying the importance of an ecological process ultimately requires evidence linking a process to unmanipulated field patterns. We suspected that such process-linked-to-pattern (PLP) studies were poorly represented in the predation risk literature, which conflicts with the confidence often given to the importance of risk effects. We reviewed 29 years of the ecological literature which revealed that there are well over 4000 articles on risk effects. Of those, 349 studies examined risk effects on prey fitness measures or abundance (i.e., non-consumptive effects) of which only 26 were PLP studies, while 275 studies examined effects on other interacting species (i.e., trait-mediated indirect effects) of which only 35 were PLP studies. PLP studies were narrowly focused taxonomically and included only three that examined unmanipulated patterns of prey abundance. Before concluding a widespread and influential role of predation-risk effects, more attention must be given to linking the process of risk effects to unmanipulated patterns observed across diverse ecosystems.
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Affiliation(s)
- Scott D Peacor
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, USA
| | - Nathan J Dorn
- Department of Biological Sciences and Institute of Environment, Florida International University, Miami, Florida, USA
| | - Justine A Smith
- Department of Wildlife, Fish, and Conservation Biology, University of California - Davis, Davis, California, USA
| | - Nicole E Peckham
- Department of Marine and Environmental Science, Northeastern University, Boston, Massachusetts, USA
| | - Michael J Cherry
- Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, Kingsville, Texas, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, USA
| | - David L Kimbro
- Department of Marine and Environmental Science, Northeastern University, Boston, Massachusetts, USA
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3
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Suraci JP, Smith JA, Chamaillé‐Jammes S, Gaynor KM, Jones M, Luttbeg B, Ritchie EG, Sheriff MJ, Sih A. Beyond spatial overlap: harnessing new technologies to resolve the complexities of predator–prey interactions. OIKOS 2022. [DOI: 10.1111/oik.09004] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | - Justine A. Smith
- Dept of Wildlife, Fish and Conservation Biology, Univ. of California Davis CA USA
| | - Simon Chamaillé‐Jammes
- CEFE, Univ. Montpellier, CNRS, EPHE, IRD Montpellier France
- Mammal Research Inst., Dept of Zoology&Entomology, Univ. of Pretoria Pretoria South Africa
| | - Kaitlyn M. Gaynor
- National Center for Ecological Analysis and Synthesis, Univ. of California Santa Barbara CA USA
| | - Menna Jones
- School of Natural Sciences, Univ. of Tasmania Tasmania Australia
| | - Barney Luttbeg
- Dept of Integrative Biology, Oklahoma State Univ. Stillwater OK USA
| | - Euan G. Ritchie
- School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin Univ. Burwood VIC Australia
| | | | - Andrew Sih
- Dept of Environmental Science and Policy, Univ. of California Davis CA USA
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4
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MacLeod KJ, Langkilde T, Heppner JJ, Howey CAF, Sprayberry K, Tylan C, Sheriff MJ. Compensating for a stressful pregnancy? Glucocorticoid treatment during gravidity reduces metabolic rate in female fence lizards post-parturition. Horm Behav 2021; 136:105072. [PMID: 34628291 DOI: 10.1016/j.yhbeh.2021.105072] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 07/26/2021] [Accepted: 09/23/2021] [Indexed: 11/23/2022]
Abstract
Reproduction is a critical part of an animal's life history, but one which incurs significant costs to survival and future reproductive potential. These physiological consequences are likely to be influenced by context - for example, if an individual is subject to environmental stressors, physiological and behavioral changes associated with reproduction may be altered. Glucocorticoids, hormones produced as part of the physiological response to stressors, may alter how reproduction affects female physiology and behavior, and therefore the outcomes of reproductive trade-offs. Glucocorticoids prioritize immediate survival over reproduction, for example through changes in immune function, metabolic rate, and foraging, which may reduce energy expenditure or increase energy gain. However, we previously found that female eastern fence lizards (Sceloporus undulatus) experiencing elevated glucocorticoid levels during gestation were nevertheless able to maintain reproductive output and body condition. Here we investigate compensatory mechanisms by which eastern fence lizard females may maintain reproduction under experimental increases in a glucocorticoid, corticosterone (CORT). We found that, although CORT-treated females had similar immune function and behavior, they had reduced metabolic rates 3-5 days post-parturition compared to control females. Given that CORT-treated females spent a similar time basking and had equal food intake compared to control females, we suggest that the reduced metabolic rate is a mechanism by which CORT-treated females maintain their energy balance and reduce the energetic costs of gestation during periods of stress. This study suggests that physiological responses to reproduction may be context-dependent and could act to minimize costs of reproduction in situations where CORT is elevated (such as during periods of environmental stress).
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Affiliation(s)
- K J MacLeod
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Department of Biology, Lund University, Sölvegatan 37, Lund 223 62, Sweden.
| | - T Langkilde
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA
| | - J J Heppner
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - C A F Howey
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Department of Biology, University of Scranton, Loyola Science Center, Scranton, PA 18510, USA
| | - K Sprayberry
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA
| | - C Tylan
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA
| | - M J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
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MacLeod KJ, Langkilde T, Venable CP, Ensminger DC, Sheriff MJ. The influence of maternal glucocorticoids on offspring phenotype in high- and low-risk environments. Behav Ecol 2021; 32:1330-1338. [PMID: 34949960 PMCID: PMC8691550 DOI: 10.1093/beheco/arab099] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/06/2021] [Accepted: 08/11/2021] [Indexed: 11/12/2022] Open
Abstract
Elevated maternal glucocorticoid levels during gestation can lead to phenotypic changes in offspring via maternal effects. Although such effects have traditionally been considered maladaptive, maternally derived glucocorticoids may adaptively prepare offspring for their future environment depending upon the correlation between maternal and offspring environments. Nevertheless, relatively few studies test the effects of prenatal glucocorticoid exposure across multiple environments. We tested the potential for ecologically relevant increases in maternal glucocorticoids in the eastern fence lizard (Sceloporus undulatus) to induce adaptive phenotypic changes in offspring exposed to high or low densities of an invasive fire ant predator. Maternal treatment had limited effects on offspring morphology and behavior at hatching, but by 10 days of age, we found maternal treatment interacted with offspring environment to alter anti-predator behaviors. We did not detect differences in early-life survival based on maternal treatment or offspring environment. Opposing selection on anti-predator behaviors from historic and novel invasive predators may confound the potential of maternal glucocorticoids to adaptively influence offspring behavior. Our test of the phenotypic outcomes of transgenerational glucocorticoid effects across risk environments provides important insight into the context-specific nature of this phenomenon and the importance of understanding both current and historic evolutionary pressures.
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Affiliation(s)
- Kirsty J MacLeod
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA, 16802, USA
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA, 16802, USA
- Department of Biology, Lund University, Sölvegatan 37, 223 62, Lund, Sweden
| | - Tracy Langkilde
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA, 16802, USA
- Intercollege Graduate Degree Program in Ecology, The Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
- Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA, 16802, USA
| | - Cameron P Venable
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA, 16802, USA
| | - David C Ensminger
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA, 16802, USA
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA, 16802, USA
- Department of Biological Sciences, San Jose State University, One Washington Square, San José, CA, 95192, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA, 02747, USA
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Kelleher V, Hunnick L, Sheriff MJ. Risk-Induced Foraging Behavior in a Free-Living Small Mammal Depends on the Interactive Effects of Habitat, Refuge Availability, and Predator Type. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.718887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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
Predators have a major influence on prey populations and broader ecosystem dynamics through both their consumptive and non-consumptive effects. Prey employ risk-induced trait responses such as shifts in habitat use or changes in foraging behavior in response to the presence of predators. Risk-induced changes in foraging depend upon both the predator community and the environmental context; however, the influence of these factors have rarely been concurrently examined in free-living animals. We investigated the interactive effects of habitat, refuge availability, and predator type on the foraging behavior of free-living white-footed mice, accounting for the abiotic factor moonlight. We used auditory calls of a local terrestrial cursorial predator and a local avian ambush predator to simulate predation risk in both a forest edge and a forest interior habitat, and measured the foraging of mice under different experimental refuge types. We found that, while mice had reduced foraging when exposed to predation risk, the degree of this response depended on an interaction among habitat, refuge use, and type of predator. Prey had the greatest reduction in foraging and used refuges the most when exposed to cursorial-hunting foxes at the open forest edge. The risk-induced reduction in foraging and the use of refuges was much weaker in the forest interior, but even here foxes elicited a greater response as compared to owls. Generally, foraging tended to decrease with increasing moonlight, but this was not significant. We suggest that it is the temporal nature of cursorial vs. ambush predators in our system that drives such effects as opposed to their hunting mode, and that prey responses to temporal hotspots of risk need further examination. Generally, our results show that wild small-mammal prey species have variable responses to predation risk depending on the environmental context in which risk occurs.
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Ensminger DC, Siegel SR, Owen DAS, Sheriff MJ, Langkilde T. Elevated glucocorticoids during gestation suggest sex-specific effects on offspring telomere lengths in a wild lizard. Comp Biochem Physiol A Mol Integr Physiol 2021; 257:110971. [PMID: 33933630 DOI: 10.1016/j.cbpa.2021.110971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 01/09/2021] [Revised: 04/06/2021] [Accepted: 04/26/2021] [Indexed: 12/30/2022]
Abstract
The effects of maternal glucocorticoids (e.g. corticosterone, CORT) on offspring interest biologists due to increasing environmental perturbations. While little is known about the impact of maternal CORT on offspring fitness, it may modulate telomere length and compromise offspring health. Here, we use a modified real-time quantitative PCR assay to assess telomere length using small DNA quantities (<60 ng). We tested the hypothesis that increased maternal CORT during gestation decreases offspring telomere length. While CORT-driven telomere shortening is well established within individuals, cross-generational effects remain unclear. We treated wild-caught gravid female eastern fence lizards (Sceloporus undulatus) with daily transdermal applications of CORT, at ecologically relevant levels, from capture to laying. Maternal CORT treatment did not alter maternal telomere length, although baseline maternal CORT concentrations had a weak, negative correlation with maternal telomere length. There was no relation between mother and offspring telomere length. There was a trend for maternal CORT treatment to shorten telomeres of sons but not daughters. Our treatment replicated exposure to a single stressor per day, likely underestimating effects seen in the wild where stressors may be more frequent. Future research should further explore fitness consequences of maternal CORT effects.
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Affiliation(s)
- David C Ensminger
- Department of Ecosystem Science and Management, The Pennsylvania State University, Forest Resources Building, University Park, PA 16802, United States of America; Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America.
| | - Sue R Siegel
- Department of Biobehavioral Health, The Pennsylvania State University, Biomarker Core Lab, University Park, PA 16802, United States of America
| | - Dustin A S Owen
- Department of Ecosystem Science and Management, The Pennsylvania State University, Forest Resources Building, University Park, PA 16802, United States of America; Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America; Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, United States of America
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, United States of America
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America; Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, United States of America
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Peacor SD, Barton BT, Kimbro DL, Sih A, Sheriff MJ. A framework and standardized terminology to facilitate the study of predation-risk effects. Ecology 2020; 101:e03152. [PMID: 32736416 DOI: 10.1002/ecy.3152] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [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: 09/12/2019] [Revised: 03/14/2020] [Accepted: 06/08/2020] [Indexed: 11/10/2022]
Abstract
The very presence of predators can strongly influence flexible prey traits such as behavior, morphology, life history, and physiology. In a rapidly growing body of literature representing diverse ecological systems, these trait (or "fear") responses have been shown to influence prey fitness components and density, and to have indirect effects on other species. However, this broad and exciting literature is burdened with inconsistent terminology that is likely hindering the development of inclusive frameworks and general advances in ecology. We examine the diverse terminology used in the literature, and discuss pros and cons of the many terms used. Common problems include the same term being used for different processes, and many different terms being used for the same process. To mitigate terminological barriers, we developed a conceptual framework that explicitly distinguishes the multiple predation-risk effects studied. These multiple effects, along with suggested standardized terminology, are risk-induced trait responses (i.e., effects on prey traits), interaction modifications (i.e., effects on prey-other-species interactions), nonconsumptive effects (i.e., effects on the fitness and density of the prey), and trait-mediated indirect effects (i.e., the effects on the fitness and density of other species). We apply the framework to three well studied systems to highlight how it can illuminate commonalities and differences among study systems. By clarifying and elucidating conceptually similar processes, the framework and standardized terminology can facilitate communication of insights and methodologies across systems and foster cross-disciplinary perspectives.
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Affiliation(s)
- Scott D Peacor
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Brandon T Barton
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, 39762, USA
| | - David L Kimbro
- Department of Marine and Environmental Science, Northeastern University, Nahant, Massachusetts, 01908, USA
| | - Andrew Sih
- Department of Environmental Science and Policy, University of California Davis, Davis, California, 95616, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, 20747, USA
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9
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Hunninck L, Palme R, Sheriff MJ. Stress as a facilitator? Territorial male impala have higher glucocorticoid levels than bachelors. Gen Comp Endocrinol 2020; 297:113553. [PMID: 32687935 DOI: 10.1016/j.ygcen.2020.113553] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 06/12/2020] [Accepted: 07/14/2020] [Indexed: 11/25/2022]
Abstract
Territoriality is a common behavioural adaptation, widespread among ungulates. Here, we tested the hypothesis that territorial individuals have higher glucocorticoid concentrations than non-territorial bachelors, in wild impala (Aepyceros melampus) in the Serengeti ecosystem. We also investigated how the relationship between territoriality and glucocorticoid levels is influenced by environmental context, specifically, food quality, population density (i.e., territory defence intensity), and herd size (i.e., mate defence effort). We collected 139 faecal samples over 4 years and analysed these for faecal glucocorticoid metabolites (FGMs). We used Normalised Difference Vegetation Index (NDVI) as a proxy for food quality, and population density was based on aerial surveys. Territorial males had, on average, higher FGM concentrations than bachelors. Increased food quality did not affect FGM levels in territorial males, but decreased FGM levels in bachelors by 78%. Greater population density increased FGM levels by 47%, but this effect was not different between territorial and bachelor males. Herd size did not affect FGM levels in territorial males. While elevated GC levels are often suggested to be repercussions of being territorial, our findings support the hypothesis that elevated GC levels may be beneficial and act as a facilitator of a male's reproductive potential. The elevated GC levels may increase the ability of territorial males to maintain a territory by increasing energy mobilisation and metabolic rate, ultimately increasing their reproductive fitness. Appreciating that long-term increases in GC levels are not simply costly but may have an adaptive, potentially facilitating role in an animal's life history is key to understanding HPA-axis reactivity and its potential in eco-physiological studies.
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Affiliation(s)
- L Hunninck
- Norwegian University of Science and Technology, Norway; University of Massachusetts Dartmouth, United States.
| | - R Palme
- University of Veterinary Medicine, Austria
| | - M J Sheriff
- University of Massachusetts Dartmouth, United States
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10
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Smith JA, Donadio E, Bidder OR, Pauli JN, Sheriff MJ, Perrig PL, Middleton AD. Where and when to hunt? Decomposing predation success of an ambush carnivore. Ecology 2020; 101:e03172. [PMID: 32852062 DOI: 10.1002/ecy.3172] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 10/23/2019] [Revised: 06/08/2020] [Accepted: 06/29/2020] [Indexed: 11/11/2022]
Abstract
Predator-prey games emerge when predators and prey dynamically respond to the behavior of one another, driving the outcomes of predator-prey interactions. Predation success is a function of the combined probabilities of encountering and capturing prey, which are influenced by both prey behavior and environmental features. While the relative importance of encounter and capture probabilities have been evaluated in a spatial framework, temporal variation in prey behavior and intrinsic catchability are likely to also affect the distribution of predation events. Using a single-predator-single-prey (puma-vicuña) system, we evaluated which factors predict predation events across both temporal and spatial dimensions of the components of predation by testing the prey-abundance hypothesis (predators select for high encounter probability) and the prey-catchability hypothesis (predators select for high relative capture probability) in time and space. We found that for both temporal and spatial analyses, neither the prey-abundance hypothesis nor the prey-catchability hypothesis alone predicted kill frequency or distribution; puma kill frequency was static throughout the diel cycle and pumas consistently selected a single habitat type when hunting, despite temporal and spatial variation in encounter rates and intrinsic catchability. Our integrated spatiotemporal analysis revealed that an interaction between time of day and habitat influences kill probability, suggesting that trade-offs in the temporal and spatial components of predation drive the probability of predation events. These findings reinforce the importance of examining both the temporal and spatial patterns of the components of predation, rather than unidimensional measures of predator or prey behavior, to comprehensively describe the feedbacks between predator and prey in the predator-prey game.
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Affiliation(s)
- Justine A Smith
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, California, 95616, USA
| | - Emiliano Donadio
- Rewilding Argentina, Estancia La Ascensión, Los Antiguos, Santa Cruz, 9041, Argentina
| | - Owen R Bidder
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA
| | - Jonathan N Pauli
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, 02747, USA
| | - Paula L Perrig
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Arthur D Middleton
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA
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11
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Sheriff MJ, Orrock JL, Ferrari MCO, Karban R, Preisser EL, Sih A, Thaler JS. Proportional fitness loss and the timing of defensive investment: a cohesive framework across animals and plants. Oecologia 2020; 193:273-283. [PMID: 32542471 DOI: 10.1007/s00442-020-04681-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 10/29/2018] [Accepted: 06/06/2020] [Indexed: 11/25/2022]
Abstract
The risk of consumption is a pervasive aspect of ecology and recent work has focused on synthesis of consumer-resource interactions (e.g., enemy-victim ecology). Despite this, theories pertaining to the timing and magnitude of defenses in animals and plants have largely developed independently. However, both animals and plants share the common dilemma of uncertainty of attack, can gather information from the environment to predict future attacks and alter their defensive investment accordingly. Here, we present a novel, unifying framework based on the way an organism's ability to defend itself during an attack can shape their pre-attack investment in defense. This framework provides a useful perspective on the nature of information use and variation in defensive investment across the sequence of attack-related events, both within and among species. It predicts that organisms with greater proportional fitness loss if attacked will gather and respond to risk information earlier in the attack sequence, while those that have lower proportional fitness loss may wait until attack is underway. This framework offers a common platform to compare and discuss consumer effects and provides novel insights into the way risk information can propagate through populations, communities, and ecosystems.
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Affiliation(s)
- Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA, USA.
| | - John L Orrock
- Department of Integrative Biology, University of Wisconsin, Madison, WI, USA
| | - Maud C O Ferrari
- Department of Biomedical Sciences, WCVM, University of Saskatchewan, Saskatoon, SK, Canada
| | - Richard Karban
- Department of Entomology, University of California, Davis, CA, USA
| | - Evan L Preisser
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
| | - Andrew Sih
- Department of Environmental Science and Policy, University of California, Davis, CA, USA
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12
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Sheriff MJ, Peacor SD, Hawlena D, Thaker M. Non-consumptive predator effects on prey population size: A dearth of evidence. J Anim Ecol 2020; 89:1302-1316. [PMID: 32215909 DOI: 10.1111/1365-2656.13213] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [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: 11/19/2018] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Abstract
There is a large and growing interest in non-consumptive effects (NCEs) of predators. Diverse and extensive evidence shows that predation risk directly influences prey traits, such as behaviour, morphology and physiology, which in turn, may cause a reduction in prey fitness components (i.e. growth rate, survival and reproduction). An intuitive expectation is that NCEs that reduce prey fitness will extend to alter population growth rate and therefore population size. However, our intensive literature search yielded only 10 studies that examined how predator-induced changes in prey traits translate to changes in prey population size. Further, the scant evidence for risk-induced changes on prey population size have been generated from studies that were performed in very controlled systems (mesocosm and laboratory), which do not have the complexity and feedbacks of natural settings. Thus, although likely that predation risk alone can alter prey population size, there is little direct empirical evidence that demonstrates that it does. There are also clear reasons that risk effects on population size may be much smaller than the responses on phenotype and fitness components that are typically measured, magnifying the need to show, rather than infer, effects on population size. Herein we break down the process of how predation risk influences prey population size into a chain of events (predation risk affects prey traits, which affect prey fitness components and population growth rate, which affect prey population size), and highlight the complexity of each transition. We illustrate how the outcomes of these transitions are not straightforward, and how environmental context strongly dictates the direction and magnitude of effects. Indeed, the high variance in prey responses is reflected in the variance of results reported in the few studies that have empirically quantified risk effects on population size. It is therefore a major challenge to predict population effects given the complexity of how environmental context interacts with predation risk and prey responses. We highlight the critical need to appreciate risk effects at each level in the chain of events, and that changes at one level cannot be assumed to translate into changes in the next because of the interplay between risk, prey responses, and the environment. The gaps in knowledge we illuminate underscore the need for more evidence to substantiate the claim that predation risk effects extend to prey population size. The lacunae we identify should inspire future studies on the impact of predation risk on population-level responses in free-living animals.
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Affiliation(s)
- Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA, USA
| | - Scott D Peacor
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA
| | - Dror Hawlena
- Risk Management Ecology Laboratory, Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
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13
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Mohlman JL, Navara KJ, Sheriff MJ, Terhune TM, Martin JA. Validation of a noninvasive technique to quantify stress in northern bobwhite ( Colinus virginianus). Conserv Physiol 2020; 8:coaa026. [PMID: 32308982 PMCID: PMC7154183 DOI: 10.1093/conphys/coaa026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 09/23/2019] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
Examination of the endocrine system through non-invasive fecal sampling may improve population management more than using demographic indicators alone. By addressing the physiological mechanisms that are influencing fitness, management actions can be proactively developed to alleviate stressors. Proactive determination of vulnerable populations is critical for species of concern, such as the Northern Bobwhite (Colinus virginianus), which have suffered decades of population decline. We validated an assay to noninvasively measure the adrenocortical response of captive reared bobwhite through fecal corticosterone metabolites (FCM). All individuals received three sequential 48-hour treatments in which samples were collected every 4 hours, including a reference period, an adrenocorticotropic hormone (ACTH) challenge and a biological stressor (exposure to a hunting dog). Reference FCM values had a mean concentration of 16.75 pg/mg (95% CrI: 13.68, 19.91) with adrenocortical activity increasing by 73% for the duration of the ACTH challenge (29.00 pg/mg; CrI: 25.01, 33.78). FCM concentrations remained similar to that of the reference levels during the biological stressor (16.56 pg/mg; CrI: 13.33, 19.92). Our study validates the use of feces to detect changes in FCM levels in our subject species but also demonstrates the complexity of FCM and the importance of both physiological and biological validation prior to field implementation.
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Affiliation(s)
- Jessica L Mohlman
- D. B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Kristen J Navara
- Department of Poultry Science, University of Georgia, Athens, GA 30602, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA, 02747, USA
| | | | - James A Martin
- D. B. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
- Savannah River Ecology Lab, University of Georgia, Athens, GA, 30602, USA
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14
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Gigliotti LC, Berg ND, Boonstra R, Cleveland SM, Diefenbach DR, Gese EM, Ivan JS, Kielland K, Krebs CJ, Kumar AV, Mills LS, Pauli JN, Underwood HB, Wilson EC, Sheriff MJ. Latitudinal variation in snowshoe hare (Lepus americanus) body mass: a test of Bergmann’s rule. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0184] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The relationship between body size and latitude has been the focus of dozens of studies across many species. However, results of testing Bergmann’s rule — that organisms in colder climates or at higher latitudes possess larger body sizes — have been inconsistent across studies. We investigated whether snowshoe hares (Lepus americanus Erxleben, 1777) follow Bergmann’s rule by investigating differences in body mass using data from six published studies and from data of 755 individual hares captured from 10 populations across North America covering 26° of north latitude. We also explored alternative hypotheses related to variation in hare body mass, including winter severity, length of growing season, elevation, and snow depth. We found body mass of hares varied throughout their range, but the drivers of body mass differed based on geographic location. In northern populations, females followed Bergmann’s rule, whereas males did not. In northern populations, male mass was related to mean snow depth. In contrast, in southern populations, body mass of both sexes was related to length of the growing season. These differences likely represent variation in the drivers of selection. Specifically, in the north, a large body size is beneficial to conserve heat because of low winter temperatures, whereas in the south, it is likely due to increased food supply associated with longer growing seasons.
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Affiliation(s)
- Laura C. Gigliotti
- Department of Forestry and Environmental Conservation, Clemson University, 261 Lehotsky Hall, Clemson, SC 29634, USA
| | - Nathan D. Berg
- U.S. Fish and Wildlife Service, National Wildlife Refuge System, Anchorage, AK 99503, USA
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Shawn M. Cleveland
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA
| | - Duane R. Diefenbach
- U.S. Geological Survey, Pennsylvania Cooperative Fish and Wildlife Research Unit, Pennsylvania State University, University Park, PA 16802, USA
| | - Eric M. Gese
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center, Department of Wildland Resources, Utah State University, Logan, UT 84322, USA
| | - Jacob S. Ivan
- Colorado Parks and Wildlife, Fort Collins, CO 80526, USA
| | - Knut Kielland
- Department of Biology and Wildlife, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Charles J. Krebs
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Alexander V. Kumar
- Wildlife Biology Program, University of Montana, Missoula, MT 59812, USA
| | - L. Scott Mills
- Wildlife Biology Program, University of Montana, Missoula, MT 59812, USA
- Office of the Vice President for Research and Creative Scholarship, University of Montana, Missoula, MT 59812, USA
| | - Jonathan N. Pauli
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - H. Brian Underwood
- U.S. Geological Survey, Patuxent Wildlife Research Center, Tunison Laboratory of Aquatic Science, Cortland, NY 13043, USA
| | - Evan C. Wilson
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Michael J. Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
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Hunninck L, May R, Jackson CR, Palme R, Røskaft E, Sheriff MJ. Consequences of climate-induced vegetation changes exceed those of human disturbance for wild impala in the Serengeti ecosystem. Conserv Physiol 2020; 8:coz117. [PMID: 32477568 PMCID: PMC7246078 DOI: 10.1093/conphys/coz117] [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] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/11/2019] [Accepted: 12/29/2019] [Indexed: 05/21/2023]
Abstract
In East Africa, climate change is predicted to reduce vegetation quality, and pervasive human disturbance has already resulted in significant declines in biodiversity. We studied the combined effects of reduced forage quality and human disturbance on faecal glucocorticoid metabolite (FGM) concentrations. We predicted that decreasing nutritional quality and increasing human disturbance would have an additive positive effect on FGM levels in wild impala (Aepyceros melampus). Employing a space-for-time approach, we used normalized difference vegetation index (NDVI) as a measure of forage quality, combined with spatially explicit proxies of human disturbance across areas of different protection management strategies in the Serengeti ecosystem. We collected 639 faecal samples, spread over 4 years, including both wet and dry seasons. Impala FGM levels increased significantly with declining NDVI and, to a lesser extent, with increasing proxies for human disturbance. However, we found no interaction between the two, such that impala had elevated FGM levels with low NDVI and low FGM levels with high NDVI regardless of human disturbance levels. This implies that impala will have high FGM levels if forage quality is poor, even with significant protection and reduced human disturbance. Understanding how animals respond to and cope with changes in forage quality and human land use across different protected areas is important for conservationists and managers to better protect species at risk and predict population viability.
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Affiliation(s)
- L Hunninck
- Department of Biology, Norwegian University of Science and
Technology, Høgskoleringen 5, 7034 Trondheim, Norway
- Corresponding author: NTNU, Høgskoleringen 1, 7491 Trondheim, Norway.
Tel: +47 474 43 361.
| | - R May
- Norwegian Institute for Nature Research, Høgskoleringen 9, 7034
Trondheim, Norway
| | - C R Jackson
- Norwegian Institute for Nature Research, Høgskoleringen 9, 7034
Trondheim, Norway
| | - R Palme
- Department of Biomedical Sciences, University of Veterinary
Medicine, Veterinärplatz 1, 1210 Vienna, Austria
| | - E Røskaft
- Department of Biology, Norwegian University of Science and
Technology, Høgskoleringen 5, 7034 Trondheim, Norway
| | - M J Sheriff
- Biology Department, University of Massachusetts, 285 Old Westport
Road, Dartmouth, MA 02747, USA
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Donelan SC, Hellmann JK, Bell AM, Luttbeg B, Orrock JL, Sheriff MJ, Sih A. Transgenerational Plasticity in Human-Altered Environments. Trends Ecol Evol 2019; 35:115-124. [PMID: 31706627 DOI: 10.1016/j.tree.2019.09.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [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: 03/29/2019] [Revised: 09/06/2019] [Accepted: 09/11/2019] [Indexed: 01/04/2023]
Abstract
Our ability to predict how species will respond to human-induced rapid environmental change (HIREC) may depend upon our understanding of transgenerational plasticity (TGP), which occurs when environments experienced by previous generations influence phenotypes of subsequent generations. TGP evolved to help organisms cope with environmental stressors when parental environments are highly predictive of offspring environments. HIREC can alter conditions that favored TGP in historical environments by reducing parents' ability to detect environmental conditions, disrupting previous correlations between parental and offspring environments, and interfering with the transmission of parental cues to offspring. Because of the propensity to produce errors in these processes, TGP will likely generate negative fitness outcomes in response to HIREC, though beneficial fitness outcomes may occur in some cases.
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Affiliation(s)
- Sarah C Donelan
- Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, USA
| | - Jennifer K Hellmann
- Department of Evolution, Ecology and Behavior, Carl R. Woese Institute for Genomic Biology, Program in Neuroscience, Program in Ecology, Evolution and Conservation, University of Illinois, Urbana Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA.
| | - Alison M Bell
- Department of Evolution, Ecology and Behavior, Carl R. Woese Institute for Genomic Biology, Program in Neuroscience, Program in Ecology, Evolution and Conservation, University of Illinois, Urbana Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA
| | - Barney Luttbeg
- Department of Integrative Biology, 501 Life Sciences West, Oklahoma State University, Stillwater, OK 74078, USA
| | - John L Orrock
- Department of Integrative Biology, 145 Noland Hall, 250 North Mills Street, University of Wisconsin, Madison, WI 53706, USA
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Andrew Sih
- Department of Environmental Science and Policy, University of California, One Shields Avenue, Davis, CA 95616, USA
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17
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Sprayberry K, Tylan C, Owen DAS, Macleod KJ, Sheriff MJ, Langkilde T. History of predator exposure affects cell-mediated immunity in female eastern fence lizards, Sceloporus undulatus (Squamata: Phrynosomatidae). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Abstract
On exposure to stressors, energy is diverted from non-urgent functions towards those important for immediate survival. The degree and nature of reallocation may be affected by the evolutionary history of the animal. The eastern fence lizard (Sceloporus undulatus) coexists in parts of its range with invasive fire ants (Solenopsis invicta), which attack and wound lizards and elevate stress-relevant hormones (corticosterone), whereas other populations have never been exposed to fire ants. We examined how a history of fire ant invasion affected the immune response in female lizards after exposure to exogenous corticosterone (mimicking exposure to a stressor) during gestation (dosing regimens differed among corticosterone-exposed lizards owing to the constraints of the original studies, but we found no evidence that this affected the outcome of the present study). A history of exposure to predatory stressors (fire ants) and corticosterone treatment affected cell-mediated immunity. Lizards from fire ant-invaded sites had a reduced immune response compared with those from uninvaded sites. Corticosterone treatment had no effect on the immune response of lizards from invaded sites but reduced the immune response of lizards from uninvaded sites. This suggests that an evolutionary history of exposure to wounding alters the immune response to corticosterone. Future work on how the immune system responds to environmental threats will be informative for the prediction and management of these threats.
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Affiliation(s)
- Kristen Sprayberry
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, USA
| | - Catherine Tylan
- Department of Biology, The Pennsylvania State University, University Park, USA
| | - Dustin A S Owen
- Department of Biology, The Pennsylvania State University, University Park, USA
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Kirsty J Macleod
- Department of Biology, The Pennsylvania State University, University Park, USA
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Michael J Sheriff
- Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, University Park, USA
- Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, USA
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18
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Owen DAS, Sheriff MJ, Heppner JJ, Gerke H, Ensminger DC, MacLeod KJ, Langkilde T. Maternal corticosterone increases thermal sensitivity of heart rate in lizard embryos. Biol Lett 2019; 15:20180718. [PMID: 30958207 DOI: 10.1098/rsbl.2018.0718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
While it is well established that maternal stress hormones, such as corticosterone (CORT), can induce transgenerational phenotypic plasticity, few studies have addressed the influence of maternal CORT on pre-natal life stages. We tested the hypothesis that experimentally increased CORT levels of gravid female eastern fence lizards ( Sceloporus undulatus) would alter within-egg embryonic phenotype, particularly heart rates. We found that embryos from CORT-treated mothers had heart rates that increased faster with increasing temperature, resulting in higher heart rates at developmentally relevant temperatures but similar heart rates at maintenance relevant temperatures, compared with embryos of control mothers. Thus, maternal CORT appears to alter the physiology of pre-natal offspring. This may speed development and decrease the amount of time spent in eggs, the most vulnerable stage of life.
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Affiliation(s)
- Dustin A S Owen
- 1 Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University , University Park, PA 16802 , USA.,2 Department of Ecosystem Science and Management, The Pennsylvania State University , University Park, PA 16802 , USA.,3 Department of Biology, The Pennsylvania State University , University Park, PA 16802 , USA
| | - Michael J Sheriff
- 2 Department of Ecosystem Science and Management, The Pennsylvania State University , University Park, PA 16802 , USA
| | - Jennifer J Heppner
- 2 Department of Ecosystem Science and Management, The Pennsylvania State University , University Park, PA 16802 , USA
| | - Hannah Gerke
- 4 Warnell School of Forestry and Natural Resources, University of Georgia , Athens, GA 30602 , USA
| | - David C Ensminger
- 2 Department of Ecosystem Science and Management, The Pennsylvania State University , University Park, PA 16802 , USA.,3 Department of Biology, The Pennsylvania State University , University Park, PA 16802 , USA
| | - Kirsty J MacLeod
- 2 Department of Ecosystem Science and Management, The Pennsylvania State University , University Park, PA 16802 , USA.,3 Department of Biology, The Pennsylvania State University , University Park, PA 16802 , USA
| | - Tracy Langkilde
- 1 Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University , University Park, PA 16802 , USA.,3 Department of Biology, The Pennsylvania State University , University Park, PA 16802 , USA
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19
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Merkle JA, Anderson NJ, Baxley DL, Chopp M, Gigliotti LC, Gude JA, Harms TM, Johnson HE, Merrill EH, Mitchell MS, Mong TW, Nelson J, Norton AS, Sheriff MJ, Tomasik E, VanBeek KR. A collaborative approach to bridging the gap between wildlife managers and researchers. J Wildl Manage 2019. [DOI: 10.1002/jwmg.21759] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jerod A. Merkle
- Department of Zoology and PhysiologyUniversity of Wyoming Department 3166, 1000 E University Ave Laramie WY 82071 USA
| | - Neil J. Anderson
- Montana Fish, Wildlife and Parks 490 N Meridian Rd Kalispell MT 59901 USA
| | - Danna L. Baxley
- The Nature Conservancy 114 Woodland Ave Lexington KY 40502 USA
| | - Matthew Chopp
- Florida Fish and Wildlife Conservation Commission 3377 E U.S. Highway 90 Lake City FL 32055 USA
| | - Laura C. Gigliotti
- Department of Forestry and Environmental ConservationClemson University 261 Lehotsky Hall Clemson SC 29634 USA
| | - Justin A. Gude
- Montana Fish, Wildlife and Parks 1420 E 6th Ave Helena MT 59620 USA
| | - Tyler M. Harms
- Iowa Department of Natural Resources 1436 255th St Boone IA 50036 USA
| | - Heather E. Johnson
- U.S. Geological Survey, Alaska Science Center 4210 University Dr Anchorage AK 99508 USA
| | - Evelyn H. Merrill
- Department of Biological SciencesUniversity of Alberta Edmonton AB T6G 2E9 Canada
| | - Michael S. Mitchell
- U.S. Geological Survey, Montana Cooperative Fish and Wildlife Research UnitWildlife Biology Program, University of Montana Missoula MT 59812 USA
| | - Tony W. Mong
- Wyoming Game and Fish Department 2820 State Highway 120 Cody WY 82414 USA
| | - Jerry Nelson
- Washington Department of Fish and WildlifeP.O. Box 43141 Olympia WA 98504 USA
| | - Andrew S. Norton
- South Dakota Game, Fish & Parks 4130 Adventure Trail Rapid City SD 57702 USA
| | - Michael J. Sheriff
- Biology Department, University of Massachusetts Dartmouth 285 Old Westport Rd North Dartmouth MA 02747 USA
| | - Eric Tomasik
- U.S. Forest Service 26 Fort Missoula Rd Missoula MT 59804 USA
| | - Kelly R. VanBeek
- U.S. Fish and Wildlife Service, 505 Science Dr, Suite A Madison WI 53711 USA
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20
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Smith JA, Donadio E, Pauli JN, Sheriff MJ, Bidder OR, Middleton AD. Habitat complexity mediates the predator-prey space race. Ecology 2019; 100:e02724. [PMID: 31157915 DOI: 10.1002/ecy.2724] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [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: 09/06/2018] [Revised: 01/22/2019] [Accepted: 02/22/2019] [Indexed: 11/12/2022]
Abstract
The spatial relationship between predator and prey is often conceptualized as a behavioral response race, in which prey avoid predators while predators track prey. Limiting habitat types can create spatial anchors for prey or predators, influencing the likelihood that the predator or prey response will dominate. Joint spatial anchors emerge when predator and prey occupy similar feeding habitat domains and risk and reward become spatially conflated, confusing predictions of which player will win the space race. These spatial dynamics of risk-foraging trade-offs are often obscured by habitat heterogeneity and community complexity in large vertebrate systems, fueling ambiguity regarding the generality of predictions from predator-prey theory. To test how habitat distribution influences the predator-prey space race, we examine correlation in puma and vicuña habitat selection and space use at two sites, one of which generates a distinct risk-foraging trade-off at a joint spatial anchor. The distribution of vegetation, which serves as both forage for vicuñas and stalking cover for pumas, differs between the sites; the llano contains a single central meadow that acts as a joint spatial anchor, while the canyon is characterized by more heterogeneous vegetation. Puma-vicuña habitat selection correlation was positive in the llano and negative in the canyon, and similarly, utilization distributions were more strongly correlated in the llano than the canyon. Vicuña locations occurred at higher values of puma habitat selection and utilization in the llano than in the canyon. Similarly, puma locations in the llano occurred at higher values of vicuña habitat selection and utilization than in the canyon. Although pumas consistently selected for and utilized vegetative and topographic cover regardless of habitat distribution, vicuñas only selected against vegetation in the heterogeneous canyon site, reducing spatial correlation with pumas. Our work suggests a joint spatial anchor favors pumas in the space race due to the inability for vicuñas to avoid crucial foraging habitat. The outcome of the predator-prey space race appears to be strongly informed by the distribution of habitat, whereby corresponding predictability of predator and prey favors predators in the spatial game.
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Affiliation(s)
- Justine A Smith
- Department of Environmental Science, Policy, and Management, University of California-Berkeley, Berkeley, California, 94720, USA
| | - Emiliano Donadio
- INIBIOMA, CONICET-Universidad Nacional Comahue, Bariloche, 8400, Argentina
| | - Jonathan N Pauli
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, 53705, USA
| | - Michael J Sheriff
- Department of Ecosystem Science and Management, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Owen R Bidder
- Department of Environmental Science, Policy, and Management, University of California-Berkeley, Berkeley, California, 94720, USA
| | - Arthur D Middleton
- Department of Environmental Science, Policy, and Management, University of California-Berkeley, Berkeley, California, 94720, USA
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21
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Smith JA, Donadio E, Pauli JN, Sheriff MJ, Middleton AD. Integrating temporal refugia into landscapes of fear: prey exploit predator downtimes to forage in risky places. Oecologia 2019; 189:883-890. [PMID: 30868375 DOI: 10.1007/s00442-019-04381-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [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: 11/18/2018] [Accepted: 03/06/2019] [Indexed: 11/25/2022]
Abstract
The landscape of fear is an important driver of prey space use. However, prey can navigate the landscape of fear by exploiting temporal refuges from predation risk. We hypothesized that diel patterns of predator and prey movement and space use would be inversely correlated due to temporal constraints on predator habitat domain. Specifically, we evaluated habitat selection and activity of the vicuña and its only predator, the puma, during three diel periods: day, dawn/dusk, and night. Pumas selected the same habitats regardless of diel period-vegetated and rugged areas that feature stalking cover for pumas-but increased their activity levels during dawn/dusk and night when they benefit from reduced detection by prey. Vicuñas avoided areas selected by pumas and reduced activity at night, but selected vegetated areas and increased activity by day and dawn/dusk. Vicuña habitat selection and movement strategies appeared to reduce the risk of encountering pumas; movement rates of pumas and vicuñas were negatively correlated across the diel cycle, and habitat selection was negatively correlated during dawn/dusk and night. Our study shows that an ambush predator's temporal activity and space use patterns interact to create diel refugia and shape the antipredator behaviors of its prey. Importantly, it is likely the very nature of ambush predators' static habitat specificity that makes predator activity important to temporally varying perceptions of risk. Prey which depend on risky habitats for foraging appear to mitigate risk by feeding when they can more easily detect predators and when predators are least active.
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Affiliation(s)
- Justine A Smith
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA.
| | - Emiliano Donadio
- INIBIOMA, CONICET-Universidad Nacional Comahue, 8400, Bariloche, Argentina
| | - Jonathan N Pauli
- Department of Forest and Wildlife Ecology, University of Wisconsin - Madison, Madison, WI, 53705, USA
| | - Michael J Sheriff
- Department of Ecosystem Science and Management, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Arthur D Middleton
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, CA, 94720, USA
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22
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MacLeod KJ, Sheriff MJ, Ensminger DC, Owen DAS, Langkilde T. Survival and reproductive costs of repeated acute glucocorticoid elevations in a captive, wild animal. Gen Comp Endocrinol 2018; 268:1-6. [PMID: 30016628 DOI: 10.1016/j.ygcen.2018.07.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/14/2018] [Accepted: 07/13/2018] [Indexed: 01/07/2023]
Abstract
Organisms are continuously encountering both predictable and unpredictable ecological stressors within their environment. The activation of the hypothalamic-pituitaryadrenal (stress) axis is a fundamental process allowing animals to cope with and respond to such encounters. A main consequence of HPA axis activation is the release of glucocorticoid hormones. Although short-term glucocorticoid elevations lead to changes in physiological and behavioral processes that are often adaptive, our understanding of fitness consequences of repeated acute elevations in glucocorticoid hormones over a longer time period is largely lacking. This is of particular current importance as animals are facing a significant increase in exposure to stressors including those associated with human-induced rapid environmental change. Here, we test fitness-relevant consequences of repeated exposure to glucocorticoids in the absence of natural challenges, by treating wild-caught gravid female eastern fence lizards (Sceloporus undulatus) with a daily transdermal dose of a glucocorticoid hormone until laying. This treatment causes an increase in plasma glucocorticoids that mimics the natural response lizards have when they encounter a stressor in the wild, without confounding effects associated with the encounter itself. This treatment reduced females' reproductive success (hatching success) and survival. Further, glucocorticoid-induced reductions in reproductive success were greater when females had experienced higher temperatures the previous winter. This demonstrates the potential significant consequences of repeated exposure to acute elevations in glucocorticoid hormones. Additionally, the costs of repeated glucocorticoid elevation may be further exaggerated by an individual's previous experience, such as the potential compounding effects of winter warming increasing animals' vulnerability to increased glucocorticoid levels during spring breeding.
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Affiliation(s)
- K J MacLeod
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Intercollege Graduate Degree Program in Ecology, The Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802, USA.
| | - M J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Intercollege Graduate Degree Program in Ecology, The Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - D C Ensminger
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802, USA
| | - D A S Owen
- Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Intercollege Graduate Degree Program in Ecology, The Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - T Langkilde
- Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Intercollege Graduate Degree Program in Ecology, The Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA; Center for Brain, Behavior and Cognition, Pennsylvania State University, University Park, PA 16802, USA
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Ensminger DC, Langkilde T, Owen DAS, MacLeod KJ, Sheriff MJ. Maternal stress alters the phenotype of the mother, her eggs and her offspring in a wild-caught lizard. J Anim Ecol 2018; 87:1685-1697. [PMID: 30074248 DOI: 10.1111/1365-2656.12891] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [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: 04/19/2018] [Accepted: 07/22/2018] [Indexed: 01/05/2023]
Abstract
While biomedical researchers have long appreciated the influence of maternally derived glucocorticoids (GCs) on offspring phenotype, ecologists have only recently begun exploring its impact in wild animals. Interpreting biomedical findings within an ecological context has posited that maternal stress, mediated by elevations of maternal GCs, may play an adaptive role preparing offspring for a stressful or rigorous environment. Yet, the influence of maternal stress on offspring phenotype has been little studied in wild animals. We experimentally elevated GCs to ecologically relevant levels (mimicking increases in maternal stress hormones following a nonlethal predator encounter, a heat challenge, or a chasing or confinement stressor) in female eastern fence lizards Sceloporus undulatus during gestation. We tested the hypothesis that maternally derived stress hormones themselves are sufficient to alter offspring phenotype. Specifically, we examined the effects of experimentally elevated maternal GCs on fitness-relevant traits of the mother, her eggs and her subsequent offspring. We found that daily maternal GC elevation: (a) increased maternal antipredator behaviours and postlaying glucose levels; (b) had no effect on egg morphology or caloric value, but altered yolk hormone (elevated GC) and nutrient content; and (c) altered offspring phenotype including stress-relevant physiology, morphology and behaviour. These findings reveal that maternally derived GCs alone can alter offspring phenotype in a wild animal, changes that may be mediated via maternal behaviour, and egg hormone and nutrient content. Understanding the ecological consequences of these effects under different environmental conditions will be critical for determining the adaptive significance of elevated maternal GCs for offspring.
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Affiliation(s)
- David C Ensminger
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania.,Department of Biology, Mueller Laboratory, Pennsylvania State University, University Park, Pennsylvania
| | - Tracy Langkilde
- Department of Biology, Mueller Laboratory, Pennsylvania State University, University Park, Pennsylvania
| | - Dustin A S Owen
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania.,Department of Biology, Mueller Laboratory, Pennsylvania State University, University Park, Pennsylvania.,Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania
| | - Kirsty J MacLeod
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania.,Department of Biology, Mueller Laboratory, Pennsylvania State University, University Park, Pennsylvania.,Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania
| | - Michael J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania.,Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania
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Sheriff MJ, Dantzer B, Love OP, Orrock JL. Error management theory and the adaptive significance of transgenerational maternal-stress effects on offspring phenotype. Ecol Evol 2018; 8:6473-6482. [PMID: 30038749 PMCID: PMC6053571 DOI: 10.1002/ece3.4074] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [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: 08/11/2017] [Revised: 02/22/2018] [Accepted: 03/15/2018] [Indexed: 12/19/2022] Open
Abstract
It is well established that circulating maternal stress hormones (glucocorticoids, GCs) can alter offspring phenotype. There is also a growing body of empirical work, within ecology and evolution, indicating that maternal GCs link the environment experienced by the mother during gestation with changes in offspring phenotype. These changes are considered to be adaptive if the maternal environment matches the offspring's environment and maladaptive if it does not. While these ideas are conceptually sound, we lack a testable framework that can be used to investigate the fitness costs and benefits of altered offspring phenotypes across relevant future environments. We present error management theory as the foundation for a framework that can be used to assess the adaptive potential of maternal stress hormones on offspring phenotype across relevant postnatal scenarios. To encourage rigorous testing of our framework, we provide field-testable hypotheses regarding the potential adaptive role of maternal stress across a diverse array of taxa and life histories, as well as suggestions regarding how our framework might provide insight into past, present, and future research. This perspective provides an informed lens through which to design and interpret experiments on the effects of maternal stress, provides a framework for predicting and testing variation in maternal stress across and within taxa, and also highlights how rapid environmental change that induces maternal stress may lead to evolutionary traps.
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Affiliation(s)
- Michael J. Sheriff
- Department of Ecosystem Science and ManagementHuck Institute of the Life SciencesPennsylvania State UniversityUniversity ParkPennsylvania
| | - Ben Dantzer
- Departments of Psychology, Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMichigan
| | - Oliver P. Love
- Department of Biological SciencesUniversity of WindsorWindsorONCanada
| | - John L. Orrock
- Department of Integrative BiologyUniversity of WisconsinMadisonWisconsin
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Sheriff MJ, Bell A, Boonstra R, Dantzer B, Lavergne SG, McGhee KE, MacLeod KJ, Winandy L, Zimmer C, Love OP. Integrating Ecological and Evolutionary Context in the Study of Maternal Stress. Integr Comp Biol 2018; 57:437-449. [PMID: 28957523 DOI: 10.1093/icb/icx105] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Maternal stress can prenatally influence offspring phenotypes and there are an increasing number of ecological studies that are bringing to bear biomedical findings to natural systems. This is resulting in a shift from the perspective that maternal stress is unanimously costly, to one in which maternal stress may be beneficial to offspring. However, this adaptive perspective is in its infancy with much progress to still be made in understanding the role of maternal stress in natural systems. Our aim is to emphasize the importance of the ecological and evolutionary context within which adaptive hypotheses of maternal stress can be evaluated. We present five primary research areas where we think future research can make substantial progress: (1) understanding maternal and offspring control mechanisms that modulate exposure between maternal stress and subsequent offspring phenotype response; (2) understanding the dynamic nature of the interaction between mothers and their environment; (3) integrating offspring phenotypic responses and measuring both maternal and offspring fitness outcomes under real-life (either free-living or semi-natural) conditions; (4) empirically testing these fitness outcomes across relevant spatial and temporal environmental contexts (both pre- and post-natal environments); (5) examining the role of maternal stress effects in human-altered environments-i.e., do they limit or enhance fitness. To make progress, it is critical to understand the role of maternal stress in an ecological context and to do that, we must integrate across physiology, behavior, genetics, and evolution.
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Affiliation(s)
- Michael J Sheriff
- Department of Ecosystem Science and Management, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Alison Bell
- School of Integrative Biology, Program in Neuroscience, and Program in Ecology, Evolution and Conservation Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana Champaign, IL 61821, USA
| | - Rudy Boonstra
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Ben Dantzer
- Department of Psychology, and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sophia G Lavergne
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Katie E McGhee
- Department of Biology, the University of the South, Sewanee, TN 37383, USA
| | - Kirsty J MacLeod
- Department of Ecosystem Science and Management, Huck Institute of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.,Department of Biology, Mueller Laboratory, Pennsylvania State University, University Park, PA 16802, USA
| | - Laurane Winandy
- CNRS, Université Toulouse 3 Paul Sabatier, ENFA, UMR5174 (Laboratoire Évolution and Diversité Biologique), 31077 Toulouse, France.,CNRS, UMR5321, Station d'Ecologie Théorique et Expérimentale, 09200 Moulis, France
| | - Cedric Zimmer
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Oliver P Love
- Department of Biological Sciences, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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Sheriff MJ, Boonstra R, Palme R, Buck CL, Barnes BM. Coping with differences in snow cover: the impact on the condition, physiology and fitness of an arctic hibernator. Conserv Physiol 2017; 5:cox065. [PMID: 29218224 PMCID: PMC5710611 DOI: 10.1093/conphys/cox065] [Citation(s) in RCA: 9] [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] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/17/2017] [Accepted: 11/06/2017] [Indexed: 06/01/2023]
Abstract
The Earth's climate is changing at an unprecedented rate and, as ecologists, we are challenged with the difficult task of predicting how individuals and populations will respond to climate-induced changes to local and global ecosystems. Although we are beginning to understand some of the responses to changing seasonality, the physiological mechanisms that may drive these responses remain unknown. Using long-term data comparing two nearby populations (<20 km apart) of free-living arctic ground squirrels in northern Alaska, we have previously shown that the timing of spring snowmelt greatly influences their phenology of hibernation and reproduction in a population and site-specific manner. Here, we integrate these site-specific phenologies with body condition, stress physiology, reproductive success and juvenile recruitment to understand phenotypic selection in the two populations. We found that at the site with relatively late spring snowmelt and early autumn snow cover: (i) adult females were larger and in better body condition but had significantly higher stress hormone levels; (ii) females had similar numbers of comparably sized offspring, but offspring had higher stress hormone levels; and (iii) offspring density was lower just prior to hibernation. Thus, adult females at the two sites appear to use different coping strategies that allow them to maintain reproductive fitness; however, marked shortening of the active season because of later snowmelt in spring and earlier snow cover in autumn may compromise juvenile recruitment. We discuss the significance of these findings within the broader context of changing animal-environment relationships.
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Affiliation(s)
- Michael J Sheriff
- Department of Ecosystem Science and Management, The Huck Institute of Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Vienna 1210, Austria
| | - C Loren Buck
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, AZ 86001, USA
| | - Brian M Barnes
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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Affiliation(s)
- Kirsty J. MacLeod
- Dept of Ecosystem Science and Management; Pennsylvania State Univ., Forest Resources Building, University Park; PA 16802 USA
- Dept of Biology; Pennsylvania State Univ., University Park; PA USA
| | | | - Rudy Boonstra
- Centre of the Neurobiology of Stress, Dept of Biological Sciences, Univ. of Toronto Scarborough; Toronto ON Canada
| | - Michael J. Sheriff
- Dept of Ecosystem Science and Management; Pennsylvania State Univ., Forest Resources Building, University Park; PA 16802 USA
- Huck Inst. of the Life Sciences, Pennsylvania State Univ., University Park; PA USA
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Fathieh S, Sheriff MJ, Ng A, Brazete S, Gullick J, Brieger D, Kritharides L, Lowe HC. High Rates of Self-Reported Depression in a Rapid Access Chest Pain Clinic (RACPC) Population From a Tertiary Metropolitan Hospital. Heart Lung Circ 2017; 27:e15-e16. [PMID: 29102434 DOI: 10.1016/j.hlc.2016.09.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 10/20/2022]
Affiliation(s)
- S Fathieh
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - M J Sheriff
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - A Ng
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - S Brazete
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - J Gullick
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - D Brieger
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - L Kritharides
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia
| | - H C Lowe
- Cardiology Department, Concord Repatriation General Hospital and University of Sydney, Sydney, NSW, Australia.
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Abstract
Hibernation provides a means of escaping the metabolic challenges associated with seasonality, yet the ability of mammals to prolong or reenter seasonal dormancy in response to extreme weather events is unclear. Here, we show that Arctic ground squirrels in northern Alaska exhibited sex-dependent plasticity in the physiology and phenology of hibernation in response to a series of late spring snowstorms in 2013 that resulted in the latest snowmelt on record. Females and nonreproductive males responded to the >1-month delay in snowmelt by extending heterothermy or reentering hibernation after several days of euthermy, leading to a >2-week delay in reproduction compared to surrounding years. In contrast, reproductive males neither extended nor reentered hibernation, likely because seasonal gonadal growth and development and subsequent testosterone release prevents a return to torpor. Our findings reveal intriguing differences in responses of males and females to climatic stressors, which can generate a phenological mismatch between the sexes.
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Sheriff MJ. The adaptive potential of maternal stress exposure in regulating population dynamics. J Anim Ecol 2016; 84:323-5. [PMID: 26247815 DOI: 10.1111/1365-2656.12334] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 01/06/2015] [Indexed: 11/28/2022]
Abstract
Ecologists, evolutionary biologists and biomedical researchers are investing great effort in understanding the impact maternal stress may have on offspring phenotypes. Bian et al. advance this field by providing evidence that density-induced maternal stress programs offspring phenotypes, resulting in direct consequences on their fitness and population dynamics, but doing so in a context-dependent manner. They suggest that intrinsic state alterations induced by maternal stress may be one ecological factor generating delayed density-dependent effects. This research highlights the connection between maternal stress and population dynamics, and the importance of understanding the adaptive potential of such effects in a context-dependent manner.
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Affiliation(s)
- Michael J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA
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Chaby LE, Sheriff MJ, Cavigelli SA, Hirrlinger AM, Lim J, Braithwaite VA. Stress During Adolescence Shapes Performance in Adulthood: Context-Dependent Effects on Foraging and Vigilance. Ethology 2016. [DOI: 10.1111/eth.12463] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Lauren E. Chaby
- Center for Brain, Behavior, and Cognition; Pennsylvania State University; University Park PA 16802 USA
- Department of Ecosystem Science & Management; Pennsylvania State University; University Park PA 16802 USA
- Huck Institutes of the Life Sciences; Pennsylvania State University; University Park PA 16802 USA
| | - Michael J. Sheriff
- Department of Ecosystem Science & Management; Pennsylvania State University; University Park PA 16802 USA
| | - Sonia A. Cavigelli
- Center for Brain, Behavior, and Cognition; Pennsylvania State University; University Park PA 16802 USA
- Huck Institutes of the Life Sciences; Pennsylvania State University; University Park PA 16802 USA
- Department of Biobehavioral Health; Pennsylvania State University; University Park PA 16802 USA
| | - Amy M. Hirrlinger
- Center for Brain, Behavior, and Cognition; Pennsylvania State University; University Park PA 16802 USA
| | - James Lim
- Center for Brain, Behavior, and Cognition; Pennsylvania State University; University Park PA 16802 USA
| | - Victoria A. Braithwaite
- Center for Brain, Behavior, and Cognition; Pennsylvania State University; University Park PA 16802 USA
- Department of Ecosystem Science & Management; Pennsylvania State University; University Park PA 16802 USA
- Department of Biology; Pennsylvania State University; University Park PA 16802 USA
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Werner JR, Krebs CJ, Donker SA, Sheriff MJ. Forest or meadow: the consequences of habitat for the condition of female arctic ground squirrels (Urocitellus parryii plesius). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2015-0100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Body condition of animals influences the likelihood of surviving harsh environmental conditions, successfully reproducing, and resisting disease. The sum of these individual components of fitness, in turn, have consequences for the growth and persistence of wildlife populations. Here we compared the body mass and condition of adult female arctic ground squirrels (Urocitellus parryii plesius (Osgood, 1900)), an obligate hibernator, in source and sink habitats. We tested the hypothesis that adult females would be in poorer condition in the boreal forest than in adjacent meadows. We found that, during spring, postpartum females in forests weighed less (405 ± 7 vs. 437 ± 11 g; mean ± SE) and were in poorer condition (mean (±SE) residual of mass over structural size = −11.0 ± 10.2 vs. 20.5 ± 6.1 g) compared with females in meadow-source habitat. However, by the onset of entrance into hibernation in August, forest squirrels had reached parity with meadow squirrels and no difference was found in mass (519 ± 13 vs. 520 ± 15 g; mean ± SE) or condition (residual index = −0.01 ± 0.01 vs. 0.03 ± 0.01; mean ± SE). We suggest that for squirrels in formerly occupied boreal forests, (i) poor spring body condition decreased reproductive success and (ii) achieving compensatory growth, via increased foraging, comes at the costs of higher predation risk. These costs likely contributed to the recent local extinction of arctic ground squirrels in boreal forest habitat.
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Affiliation(s)
- Jeffery R. Werner
- Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
| | - Charles J. Krebs
- Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
| | - Scott A. Donker
- Alberta Environment and Sustainable Resource Development, 9920 108 Street, Edmonton, AB T5K 2M4, Canada
| | - Michael J. Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16802, USA
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Orrock JL, Sih A, Ferrari MC, Karban R, Preisser EL, Sheriff MJ, Thaler JS. Error management in plant allocation to herbivore defense. Trends Ecol Evol 2015; 30:441-5. [DOI: 10.1016/j.tree.2015.06.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 06/05/2015] [Accepted: 06/08/2015] [Indexed: 10/23/2022]
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Chaby LE, Sheriff MJ, Hirrlinger AM, Braithwaite VA. Can we understand how developmental stress enhances performance under future threat with the Yerkes-Dodson law? Commun Integr Biol 2015; 8:e1029689. [PMID: 26479861 PMCID: PMC4594369 DOI: 10.1080/19420889.2015.1029689] [Citation(s) in RCA: 15] [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] [Received: 02/25/2015] [Accepted: 03/10/2015] [Indexed: 11/24/2022] Open
Abstract
Recently we have shown that adult rats exposed to chronic stress during adolescence increase foraging performance in high-threat conditions by 43% compared to rats reared without stress. Our findings suggest that stress during adolescence can prepare rats to better function under future threat, which supports hypotheses describing an adaptive role for the long-term consequences of early stress (e.g. the thrifty phenotype and maternal mismatch hypotheses). These hypotheses often predict that early stress will impair performance in low-threat conditions later in life. However, we did not find any difference in performance under low-threat conditions between adolescent-stressed and unstressed adult animals. To understand why stress during adolescence may affect performance in high-threat but not in low-threat conditions, we discuss our findings in the framework of the Yerkes-Dodson law, a key precept of psychology that has been used for over a century to describe how stress affects performance.
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Affiliation(s)
- Lauren E Chaby
- Center for Brain, Behavior, and Cognition; Pennsylvania State University ; University Park, PA, USA
| | - Michael J Sheriff
- Center for Brain, Behavior, and Cognition; Pennsylvania State University ; University Park, PA, USA
| | - Amy M Hirrlinger
- Center for Brain, Behavior, and Cognition; Pennsylvania State University ; University Park, PA, USA
| | - Victoria A Braithwaite
- Center for Brain, Behavior, and Cognition; Pennsylvania State University ; University Park, PA, USA ; Department of Ecosystem Science & Management; Pennsylvania State University ; University Park, PA, USA ; Department of Biology; Pennsylvania State University ; University Park, PA, USA
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Chaby LE, Sheriff MJ, Hirrlinger AM, Braithwaite VA. Does early stress prepare individuals for a stressful future? Stress during adolescence improves foraging under threat. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.03.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Werner JR, Krebs CJ, Donker SA, Boonstra R, Sheriff MJ. Arctic ground squirrel population collapse in the boreal forests of the Southern Yukon. Wildl Res 2015. [DOI: 10.1071/wr14240] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context
The arctic ground squirrel (Urocitellus parryii) comprised 17% of the biomass of herbivores in the Yukon boreal forest during the summer months from 1987 to 1996 and was responsible for 23% of the energy flow at the herbivore level. By 2000, ground squirrel populations in this region collapsed to nearly zero and have remained there.
Aims
We summarise the population monitoring (since 1975) and recent experimental work that has been done on this key herbivore in the Kluane area of the southern Yukon to test one mechanistic hypothesis as the possible explanation for this population collapse and subsequent lack of recovery: predation.
Methods
Ground squirrels are the preferred summer prey of bird and mammal predators when snowshoe hare (Lepus americanus) populations are declining. We used translocations into formerly occupied habitat and radiotelemetry to determine movements and causes of death from 2009 to 2014. We surveyed 158 sites between 2008 and 2013 to measure the disappearance of colonies in alpine and forest habitats over 25 000 km2.
Key results
Ground squirrels from 2000 to 2013 comprised a small fraction of the herbivore biomass in the boreal forest zone, down from 17% earlier. Most forest populations (~95%) are currently extinct, whereas just over half (65%) of low-elevation meadow populations are locally extinct. One hypothesis is that ground squirrels in the forest have been driven into a predator pit from which they cannot recover. They remain abundant in alpine tundra (93% occupancy rate) and around airport runways and human habitations (97% occupancy), but there is no apparent dispersal from alpine areas down into the boreal forest.
Conclusion
The predator pit hypothesis is a likely explanation for the initial collapse and sustained decline in population size from 2000 to 2013. Recent attenuation of the hare cycle and milder winter climate have allowed shrubs to expand throughout the forest, thereby reducing visibility and increasing predation risk. This conclusion will be tested in further research using reintroductions to formerly occupied sites.
Implication
If the loss of this herbivore from the boreal forest is not reversed, predator pressure on the other major herbivores of the montane forest zone is likely to change significantly.
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Sheriff MJ, Thaler JS. Ecophysiological effects of predation risk; an integration across disciplines. Oecologia 2014; 176:607-11. [DOI: 10.1007/s00442-014-3105-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 09/22/2014] [Indexed: 01/16/2023]
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Dantzer B, Fletcher QE, Boonstra R, Sheriff MJ. Measures of physiological stress: a transparent or opaque window into the status, management and conservation of species? Conserv Physiol 2014; 2:cou023. [PMID: 27293644 PMCID: PMC4732472 DOI: 10.1093/conphys/cou023] [Citation(s) in RCA: 255] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/08/2014] [Accepted: 05/11/2014] [Indexed: 05/18/2023]
Abstract
Conservation physiology proposes that measures of physiological stress (glucocorticoid levels) can be used to assess the status and future fate of natural populations. Increases in glucocorticoids may reflect a more challenging environment, suggesting that the influence of human activities on free-living animals could be quantified by measuring glucocorticoids. Biomedical studies suggest that chronic increases in glucocorticoids can have detrimental effects on survival and reproduction, which could influence the viability of populations. Here, we discuss the use of measurements of glucocorticoids in conservation physiology. We first provide an overview of the different methods to quantify glucocorticoids and their utility in conservation physiology. We then discuss five questions we think are essential for conservation physiologists to address. We highlight how intrinsic (e.g. sex, reproductive status, age, recent experiences) and ecological factors (e.g. predation, food availability, snowfall) can, by themselves or through their interactions with anthropogenic disturbances, affect the physiological stress response and mask any general patterns about the effects of anthropogenic disturbances on glucocorticoids. Using a meta-analysis, we show that anthropogenic disturbances are consistently associated with increased glucocorticoids regardless of the type of human disturbance. We also show that males may be more sensitive to anthropogenic disturbances than females and that faecal glucocorticoids, but not baseline plasma glucocorticoids, consistently increase in response to anthropogenic disturbances. Finally, we discuss how increases in glucocorticoids in free-living animals can sometimes enhance survival and reproduction. Unfortunately, our literature analysis indicates that this observation has not yet gained traction, and very few studies have shown that increases in glucocorticoid levels resulting from anthropogenic disturbances decrease survival or reproduction. We think that the use of measures of glucocorticoids in conservation physiology has tremendous potential, but there are still a number of methodological concerns, in addition to several crucial questions that should be addressed.
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Affiliation(s)
- Ben Dantzer
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Department of Psychology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Quinn E. Fletcher
- Département de biologie, chimie et geographie, Université du Québec á Rimouski, Rimouski, QC, Canada G5L 3A1
| | - Rudy Boonstra
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, Toronto, ON, Canada M1C 1A4
| | - Michael J. Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, PA 16801, USA
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Sheriff MJ, Fridinger RW, Tøien Ø, Barnes BM, Buck CL. Metabolic rate and prehibernation fattening in free-living arctic ground squirrels. Physiol Biochem Zool 2013; 86:515-27. [PMID: 23995482 DOI: 10.1086/673092] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hibernating mammals become sequestered and cease foraging during prolonged seasonal periods of reduced or unpredictable food availability and instead rely on cached food and/or endogenous reserves of fat and protein accumulated during the previous active season. The gain in weight is due to increased food consumption, but it also has been hypothesized that hibernators maximize rates of fattening by decreasing costs of maintenance before weight gain, reflected in reduced resting metabolic rate (RMR). We recorded repeated measures of total body, lean, and fat mass in individual adult male and female arctic ground squirrels across their active season and found that squirrels increased body mass by 42% (males) and 62% (females). This gain was achieved through a 17% increase in lean mass and a 7-8-fold increase in fat mass; however, mass gain was not linear and patterns differed between sexes. Contrary to our hypothesis, decreases in RMR were not associated with rapid mass gain. We found RMR of males increased (whole-animal RMR or lean-mass-specific RMR) or remained constant (mass-specific RMR) for most of the active season and decreased only after the majority of mass had been gained. In females, although RMR (whole-animal, mass-specific, and lean-mass RMR) generally decreased across the active season, the greatest decrease occurred late in the active season after the majority of mass had been gained. In conclusion, arctic ground squirrels do not trade off metabolism to facilitate rates of weight gain before hibernation, but they do use energy sparing strategies before hibernation that help maintain peak mass.
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Affiliation(s)
- Michael J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Sheriff MJ, Richter MM, Buck CL, Barnes BM. Changing seasonality and phenological responses of free-living male arctic ground squirrels: the importance of sex. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120480. [PMID: 23836786 DOI: 10.1098/rstb.2012.0480] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Many studies have addressed the effects of climate change on species as a whole; however, few have examined the possibility of sex-specific differences. To understand better the impact that changing patterns of snow-cover have on an important resident Arctic mammal, we investigated the long-term (13 years) phenology of hibernating male arctic ground squirrels living at two nearby sites in northern Alaska that experience significantly different snow-cover regimes. Previously, we demonstrated that snow-cover influences the timing of phenological events in females. Our results here suggest that the end of heterothermy in males is influenced by soil temperature and an endogenous circannual clock, but timing of male emergence from hibernation is influenced by the timing of female emergence. Males at both sites, Atigun and Toolik, end heterothermy on the same date in spring, but remain in their burrows while undergoing reproductive maturation. However, at Atigun, where snowmelt and female emergence occur relatively early, males emerge 8 days earlier than those at Toolik, maintaining a 12-day period between male and female emergence found at each site, but reducing the pre-emergence euthermic period that is critical for reproductive maturation. This sensitivity in timing of male emergence to female emergence will need to be matched by phase shifts in the circannual clock and responsiveness to environmental factors that time the end of heterothermy, if synchrony in reproductive readiness between the sexes is to be preserved in a rapidly changing climate.
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Affiliation(s)
- Michael J Sheriff
- Department of Ecosystem Science and Management, Pennsylvania State University, 117 Forest Resources Building, University Park, PA 16802, USA.
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Helm B, Ben-Shlomo R, Sheriff MJ, Hut RA, Foster R, Barnes BM, Dominoni D. Annual rhythms that underlie phenology: biological time-keeping meets environmental change. Proc Biol Sci 2013; 280:20130016. [PMID: 23825201 DOI: 10.1098/rspb.2013.0016] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Seasonal recurrence of biological processes (phenology) and its relationship to environmental change is recognized as being of key scientific and public concern, but its current study largely overlooks the extent to which phenology is based on biological time-keeping mechanisms. We highlight the relevance of physiological and neurobiological regulation for organisms' responsiveness to environmental conditions. Focusing on avian and mammalian examples, we describe circannual rhythmicity of reproduction, migration and hibernation, and address responses of animals to photic and thermal conditions. Climate change and urbanization are used as urgent examples of anthropogenic influences that put biological timing systems under pressure. We furthermore propose that consideration of Homo sapiens as principally a 'seasonal animal' can inspire new perspectives for understanding medical and psychological problems.
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Affiliation(s)
- Barbara Helm
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK.
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Affiliation(s)
- Michael Clinchy
- Department of Biology; University of Victoria; Victoria; British Columbia; V8W 3N5; Canada
| | - Michael J. Sheriff
- Institute of Arctic Biology; University of Alaska Fairbanks; Fairbanks; Alaska; 99775; USA
| | - Liana Y. Zanette
- Department of Biology; University of Western Ontario; London; Ontario; N6A 5B7; Canada
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Love OP, McGowan PO, Sheriff MJ. Maternal adversity and ecological stressors in natural populations: the role of stress axis programming in individuals, with implications for populations and communities. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2012.02040.x] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Oliver P. Love
- Department of Biological Sciences; University of Windsor; 401 Sunset Avenue; Windsor; Ontario; N9B 3P4; Canada
| | - Patrick O. McGowan
- Department of Biological Sciences; University of Toronto Scarborough; 1265 Military Trail; Toronto; Ontario; M1C 1A4; Canada
| | - Michael J. Sheriff
- Institute of Arctic Biology; University of Alaska Fairbanks; 902 N. Koyukuk Dr; Fairbanks; Alaska; 99775; USA
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Sheriff MJ, Williams CT, Kenagy GJ, Buck CL, Barnes BM. Thermoregulatory changes anticipate hibernation onset by 45 days: data from free-living arctic ground squirrels. J Comp Physiol B 2012; 182:841-7. [PMID: 22526260 DOI: 10.1007/s00360-012-0661-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 03/27/2012] [Accepted: 04/01/2012] [Indexed: 11/26/2022]
Abstract
Hibernation is a strategy of reducing energy expenditure, body temperature (T(b)) and activity used by endotherms to escape unpredictable or seasonally reduced food availability. Despite extensive research on thermoregulatory adjustments during hibernation, less is known about transitions in thermoregulatory state, particularly under natural conditions. Laboratory studies on hibernating ground squirrels have demonstrated that thermoregulatory adjustments may occur over short intervals when animals undergo several brief, preliminary torpor bouts prior to entering multiday torpor. These short torpor bouts have been suggested to reflect a resetting of hypothalamic regions that control T(b) or to precondition animals before they undergo deep, multiday torpor. Here, we examined continuous records of T(b) in 240 arctic ground squirrels (Urocitellus parryii) prior to hibernation in the wild and in captivity. In free-living squirrels, T(b) began to decline 45 days prior to hibernation, and average T(b) had decreased 4.28 °C at the onset of torpor. Further, we found that 75 % of free-living squirrels and 35 % of captive squirrels entered bouts of multiday torpor with a single T(b) decline and without previously showing short preliminary bouts. This study provides evidence that adjustments in the thermoregulatory component of hibernation begin far earlier than previously demonstrated. The gradual reduction in T(b) is likely a component of the suite of metabolic and behavioral adjustments, controlled by an endogenous, circannual rhythm, that vary seasonally in hibernating ground squirrels.
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Affiliation(s)
- Michael J Sheriff
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
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Clinchy M, Schulkin J, Zanette LY, Sheriff MJ, McGowan PO, Boonstra R. The Neurological Ecology of Fear: Insights Neuroscientists and Ecologists Have to Offer one Another. Front Behav Neurosci 2011; 4:21. [PMID: 21629856 PMCID: PMC3084442 DOI: 10.3389/fnbeh.2011.00021] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 04/09/2011] [Indexed: 11/13/2022] Open
Abstract
That the fear and stress of life-threatening experiences can leave an indelible trace on the brain is most clearly exemplified by post-traumatic stress disorder (PTSD). Many researchers studying the animal model of PTSD have adopted utilizing exposure to a predator as a life-threatening psychological stressor, to emulate the experience in humans, and the resulting body of literature has demonstrated numerous long-lasting neurological effects paralleling those in PTSD patients. Even though much more extreme, predator-induced fear and stress in animals in the wild was, until the 1990s, not thought to have any lasting effects, whereas recent experiments have demonstrated that the effects on free-living animals are sufficiently long-lasting to even affect reproduction, though the lasting neurological effects remain unexplored. We suggest neuroscientists and ecologists both have much to gain from collaborating in studying the neurological effects of predator-induced fear and stress in animals in the wild. We outline the approaches taken in the lab that appear most readily translatable to the field, and detail the advantages that studying animals in the wild can offer researchers investigating the "predator model of PTSD."
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Affiliation(s)
- Michael Clinchy
- Department of Biology, University of Victoria Victoria, BC, Canada
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Sheriff MJ, Krebs CJ, Boonstra R. From process to pattern: how fluctuating predation risk impacts the stress axis of snowshoe hares during the 10-year cycle. Oecologia 2011; 166:593-605. [PMID: 21246218 DOI: 10.1007/s00442-011-1907-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 01/03/2011] [Indexed: 11/27/2022]
Abstract
Predation is a central organizing process affecting populations and communities. Traditionally, ecologists have focused on the direct effects of predation--the killing of prey. However, predators also have significant sublethal effects on prey populations. We investigated how fluctuating predation risk affected the stress physiology of a cyclic population of snowshoe hares (Lepus americanus) in the Yukon, finding that they are extremely sensitive to the fluctuating risk of predation. In years of high predator numbers, hares had greater plasma cortisol levels at capture, greater fecal cortisol metabolite levels, a greater plasma cortisol response to a hormone challenge, a greater ability to mobilize energy and poorer body condition. These indices of stress had the same pattern within years, during the winter and over the breeding season when the hare:lynx ratio was lowest and the food availability the worst. Previously we have shown that predator-induced maternal stress lowers reproduction and compromises offspring's stress axis. We propose that predator-induced changes in hare stress physiology affect their demography through negative impacts on reproduction and that the low phase of cyclic populations may be the result of predator-induced maternal stress reducing the fitness of progeny. The hare population cycle has far reaching ramifications on predators, alternate prey, and vegetation. Thus, predation is the predominant organizing process for much of the North American boreal forest community, with its indirect signature--stress in hares--producing a pattern of hormonal changes that provides a sensitive reflection of fluctuating predator pressure that may have long-term demographic consequences.
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Affiliation(s)
- Michael J Sheriff
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.
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Sheriff MJ, Kenagy GJ, Richter M, Lee T, Tøien Ø, Kohl F, Buck CL, Barnes BM. Phenological variation in annual timing of hibernation and breeding in nearby populations of Arctic ground squirrels. Proc Biol Sci 2010; 278:2369-75. [PMID: 21177687 DOI: 10.1098/rspb.2010.2482] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ecologists need an empirical understanding of physiological and behavioural adjustments that animals can make in response to seasonal and long-term variations in environmental conditions. Because many species experience trade-offs between timing and duration of one seasonal event versus another and because interacting species may also shift phenologies at different rates, it is possible that, in aggregate, phenological shifts could result in mismatches that disrupt ecological communities. We investigated the timing of seasonal events over 14 years in two Arctic ground squirrel populations living 20 km apart in Northern Alaska. At Atigun River, snow melt occurred 27 days earlier and snow cover began 17 days later than at Toolik Lake. This spatial differential was reflected in significant variation in the timing of most seasonal events in ground squirrels living at the two sites. Although reproductive males ended seasonal torpor on the same date at both sites, Atigun males emerged from hibernation 9 days earlier and entered hibernation 5 days later than Toolik males. Atigun females emerged and bred 13 days earlier and entered hibernation 9 days earlier than those at Toolik. We propose that this variation in phenology over a small spatial scale is likely generated by plasticity of physiological mechanisms that may also provide individuals the ability to respond to variation in environmental conditions over time.
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Affiliation(s)
- Michael J Sheriff
- Institute of Arctic Biology, University of Alaska, Fairbanks, 902 North Koyukuk Drive, Fairbanks, AK 99775, USA.
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Sheriff MJ, Krebs CJ, Boonstra R. The ghosts of predators past: population cycles and the role of maternal programming under fluctuating predation risk. Ecology 2010; 91:2983-94. [DOI: 10.1890/09-1108.1] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Michael J. Sheriff
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 Canada
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4 Canada
| | - Charles J. Krebs
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4 Canada
| | - Rudy Boonstra
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 Canada
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Sheriff MJ, Krebs CJ, Boonstra R. Assessing stress in animal populations: Do fecal and plasma glucocorticoids tell the same story? Gen Comp Endocrinol 2010; 166:614-9. [PMID: 20051245 DOI: 10.1016/j.ygcen.2009.12.017] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 12/10/2009] [Accepted: 12/28/2009] [Indexed: 10/20/2022]
Abstract
Many studies have recently focused on stress as a marker of an animal's well being. Since animals respond to a stressor by increasing their glucocorticoid (GC) levels there has been much interest in measuring these hormones. Fecal GC analyses have been used in a wide range of studies as they are an easily obtained, non-invasive measure of these stress hormones. However, these analyses rest on two major assumptions. First, they assume that fecal GC metabolites reflect free, biologically active levels of GCs in the plasma. Second, they assume that differences in fecal GC metabolite levels among animals are an accurate reflection of their physiological state and thus of their ability to respond to a stressor. We tested these assumptions in a population of free-ranging snowshoe hares (Lepus americanus) in the southwestern Yukon, from 2006 to 2008. Both assumptions were verified. Plasma free cortisol levels mirrored bile and fecal cortisol metabolite (FCM) levels, but plasma total cortisol levels did not. Differences in FCM concentrations among hares robustly predicted their response to a hormonal challenge. Hares with higher FCM concentrations showed a greater resistance to the suppression of their free plasma cortisol following a dexamethasone injection and a more marked increase of free plasma cortisol following an ACTH injection. Furthermore, we found that changes in FCM concentrations in autumn and winter over two years reliably tracked changes in plasma free cortisol levels obtained from the hormonal challenge test. These results indicate that both fecal and plasma measures of an animal's stress physiology are concordant: they tell the same story.
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Affiliation(s)
- Michael J Sheriff
- Centre for the Neurobiology of Stress, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ont., Canada M1C 1A4.
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Sheriff MJ, Speakman JR, Kuchel L, Boutin S, Humphries MM. The cold shoulder: free-ranging snowshoe hares maintain a low cost of living in cold climates. CAN J ZOOL 2009. [DOI: 10.1139/z09-087] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hypothesis that cold air temperatures (Ta) constrain the metabolic diversity of high-latitude endotherms is based on the observation among birds and mammals that mean field metabolic rate (FMR) increases, whereas the variability of FMR decreases, from the warm tropics to the cold poles. However, there is a paucity of FMR measurements from above 60° latitude and below 0 °C. We measured the daily energy expenditure of a high-latitude population of free-ranging snowshoe hares ( Lepus americanus Erxleben, 1777) in Yukon, Canada, in winter (Ta-mean = –16.4 °C) and in autumn (Ta-mean = 0.5 °C). Doubly labelled water measures of FMR were approximately 20% lower in winter than in autumn, and were a similar, low multiple of resting metabolic rate in both seasons (2.04 and 1.94, respectively). The mass-corrected FMR of snowshoe hares in winter was only half the value predicted by extrapolating the relationship between FMR and Ta > 0 to –16.4 °C. These results contribute to an emerging pattern of a reversal in the relationship between FMR and Ta in free-ranging mammals from negative above 0 °C to positive below 0 °C. We refer to the positive, low Ta portion of this relationship as the cold shoulder, and suggest that it may reflect the general necessity for free-ranging mammals to use behavioural and (or) physiological means to conserve energy during long winters when cold conditions coincide with resource scarcity.
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Affiliation(s)
- Michael J. Sheriff
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
- School of Biological Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - J. R. Speakman
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
- School of Biological Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - L. Kuchel
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
- School of Biological Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - S. Boutin
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
- School of Biological Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - M. M. Humphries
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Centre for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, ON M1C 1A4, Canada
- School of Biological Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
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