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Pocius VM, Cibotti S, Ray S, Ankoma-Darko O, McCartney NB, Schilder RJ, Ali JG. Impacts of larval host plant species on dispersal traits and free-flight energetics of adult butterflies. Commun Biol 2022; 5:469. [PMID: 35577926 PMCID: PMC9110344 DOI: 10.1038/s42003-022-03396-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 04/22/2022] [Indexed: 12/03/2022] Open
Abstract
Animals derive resources from their diet and allocate them to organismal functions such as growth, maintenance, reproduction, and dispersal. How variation in diet quality can affect resource allocation to life-history traits, in particular those important to locomotion and dispersal, is poorly understood. We hypothesize that, particularly for specialist herbivore insects that are in co-evolutionary arms races with host plants, changes in host plant will impact performance. From their coevolutionary arms-race with plants, to a complex migratory life history, Monarch butterflies are among the most iconic insect species worldwide. Population declines initiated international conservation efforts involving the replanting of a variety of milkweed species. However, this practice was implemented with little regard for how diverse defensive chemistry of milkweeds experienced by monarch larvae may affect adult fitness traits. We report that adult flight muscle investment, flight energetics, and maintenance costs depend on the host plant species of larvae, and correlate with concentration of milkweed-derived cardenolides sequestered by adults. Our findings indicate host plant species can impact monarchs by affecting fuel requirements for flight. The growth of muscle and flight performance in monarch butterflies is influenced by the plant species the larvae grow on.
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Affiliation(s)
- Victoria M Pocius
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL, USA
| | - Staci Cibotti
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Swayamjit Ray
- Department of Plant Pathology, Cornell University, Ithaca, NY, USA
| | - Obenewa Ankoma-Darko
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Nathaniel B McCartney
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Rudolf J Schilder
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA.
| | - Jared G Ali
- Department of Entomology, The Pennsylvania State University, University Park, PA, USA.
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Monarchs Reared in Winter in California Are Not Large Enough to Be Migrants. Comment on James et al. First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California. Insects 2021, 12, 946. INSECTS 2022; 13:insects13010063. [PMID: 35055906 PMCID: PMC8778705 DOI: 10.3390/insects13010063] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/01/2021] [Accepted: 01/01/2022] [Indexed: 01/19/2023]
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Pocius VM, Majewska AA, Freedman MG. The Role of Experiments in Monarch Butterfly Conservation: A Review of Recent Studies and Approaches. ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA 2022; 115:10-24. [PMID: 35069967 PMCID: PMC8764570 DOI: 10.1093/aesa/saab036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Indexed: 06/14/2023]
Abstract
Monarch butterflies (Danaus plexippus) (Lepidoptera Danaidae Danaus plexippus (Linnaeus)) are an iconic species of conservation concern due to declines in the overwintering colonies over the past twenty years. Because of this downward trend in overwintering numbers in both California and Mexico, monarchs are currently considered 'warranted-but-precluded' for listing under the Endangered Species Act. Monarchs have a fascinating life history and have become a model system in chemical ecology, migration biology, and host-parasite interactions, but many aspects of monarch biology important for informing conservation practices remain unresolved. In this review, we focus on recent advances using experimental and genetic approaches that inform monarch conservation. In particular, we emphasize three areas of broad importance, which could have an immediate impact on monarch conservation efforts: 1) breeding habitat and host plant use, 2) natural enemies and exotic caterpillar food plants, and 3) the utility of genetic and genomic approaches for understanding monarch biology and informing ongoing conservation efforts. We also suggest future studies in these areas that could improve our understanding of monarch behavior and conservation.
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Affiliation(s)
- Victoria M Pocius
- Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, USA
| | | | - Micah G Freedman
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
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Freedman MG, Roode JC, Forister ML, Kronforst MR, Pierce AA, Schultz CB, Taylor OR, Crone EE. Are eastern and western monarch butterflies distinct populations? A review of evidence for ecological, phenotypic, and genetic differentiation and implications for conservation. CONSERVATION SCIENCE AND PRACTICE 2021. [DOI: 10.1111/csp2.432] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Affiliation(s)
- Micah G. Freedman
- Department of Ecology & Evolution University of Chicago Chicago Illinois USA
- Center for Population Biology University of California, Davis Davis California USA
| | | | | | - Marcus R. Kronforst
- Department of Ecology & Evolution University of Chicago Chicago Illinois USA
| | - Amanda A. Pierce
- United States Environmental Protection Agency Washington District of Columbia USA
| | - Cheryl B. Schultz
- School of Biological Sciences, Washington State University Vancouver Washington USA
| | - Orley R. Taylor
- Department of Ecology and Evolutionary Biology University of Kansas Lawrence Kansas USA
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Potts AS, Hunter MD. Unraveling the roles of genotype and environment in the expression of plant defense phenotypes. Ecol Evol 2021; 11:8542-8561. [PMID: 34257915 PMCID: PMC8258211 DOI: 10.1002/ece3.7639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/06/2021] [Indexed: 11/09/2022] Open
Abstract
Phenotypic variability results from interactions between genotype and environment and is a major driver of ecological and evolutionary interactions. Measuring the relative contributions of genetic variation, the environment, and their interaction to phenotypic variation remains a fundamental goal of evolutionary ecology.In this study, we assess the question: How do genetic variation and local environmental conditions interact to influence phenotype within a single population? We explored this question using seed from a single population of common milkweed, Asclepias syriaca, in northern Michigan. We first measured resistance and resistance traits of 14 maternal lines in two common garden experiments (field and greenhouse) to detect genetic variation within the population. We carried out a reciprocal transplant experiment with three of these maternal lines to assess effects of local environment on phenotype. Finally, we compared the phenotypic traits measured in our experiments with the phenotypic traits of the naturally growing maternal genets to be able to compare relative effect of genetic and environmental variation on naturally occurring phenotypic variation. We measured defoliation levels, arthropod abundances, foliar cardenolide concentrations, foliar latex exudation, foliar carbon and nitrogen concentrations, and plant growth.We found a striking lack of correlation in trait expression of the maternal lines between the common gardens, or between the common gardens and the naturally growing maternal genets, suggesting that environment plays a larger role in phenotypic trait variation of this population. We found evidence of significant genotype-by-environment interactions for all traits except foliar concentrations of nitrogen and cardenolide. Milkweed resistance to chewing herbivores was associated more strongly with the growing environment. We observed no variation in foliar cardenolide concentrations among maternal lines but did observe variation among maternal lines in foliar latex exudation.Overall, our data reveal powerful genotype-by-environment interactions on the expression of most resistance traits in milkweed.
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Affiliation(s)
- Abigail S. Potts
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
| | - Mark D. Hunter
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
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Talla V, Pierce AA, Adams KL, de Man TJB, Nallu S, Villablanca FX, Kronforst MR, de Roode JC. Genomic evidence for gene flow between monarchs with divergent migratory phenotypes and flight performance. Mol Ecol 2020; 29:2567-2582. [PMID: 32542770 DOI: 10.1111/mec.15508] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 06/05/2020] [Indexed: 12/24/2022]
Abstract
Monarch butterflies are known for their spectacular annual migration in eastern North America, with millions of monarchs flying up to 4,500 km to overwintering sites in central Mexico. Monarchs also live west of the Rocky Mountains, where they travel shorter distances to overwinter along the Pacific Coast. It is often assumed that eastern and western monarchs form distinct evolutionary units, but genomic studies to support this notion are lacking. We used a tethered flight mill to show that migratory eastern monarchs have greater flight performance than western monarchs, consistent with their greater migratory distances. However, analysing more than 20 million SNPs in 43 monarch genomes, we found no evidence for genomic differentiation between eastern and western monarchs. Genomic analysis also showed identical and low levels of genetic diversity, and demographic analyses indicated similar effective population sizes and ongoing gene flow between eastern and western monarchs. Gene expression analysis of a subset of candidate genes during active flight revealed differential gene expression related to nonmuscular motor activity. Our results demonstrate that eastern and western monarchs maintain migratory differences despite ongoing gene flow, and suggest that migratory differences between eastern and western monarchs are not driven by select major-effects alleles. Instead, variation in migratory distance and destination may be driven by environmentally induced differential gene expression or by many alleles of small effect.
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Affiliation(s)
- Venkat Talla
- Department of Biology, Emory University, Atlanta, GA, USA
| | | | - Kandis L Adams
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Tom J B de Man
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Sumitha Nallu
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
| | - Francis X Villablanca
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA, USA
| | - Marcus R Kronforst
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
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Decker LE, Hunter MD. Interspecific variation and elevated CO 2 influence the relationship between plant chemical resistance and regrowth tolerance. Ecol Evol 2020; 10:5416-5430. [PMID: 32607163 PMCID: PMC7319169 DOI: 10.1002/ece3.6284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 03/30/2020] [Indexed: 12/04/2022] Open
Abstract
To understand how comprehensive plant defense phenotypes will respond to global change, we investigated the legacy effects of elevated CO2 on the relationships between chemical resistance (constitutive and induced via mechanical damage) and regrowth tolerance in four milkweed species (Asclepias). We quantified potential resistance and tolerance trade-offs at the physiological level following simulated mowing, which are relevant to milkweed ecology and conservation. We examined the legacy effects of elevated CO2 on four hypothesized trade-offs between the following: (a) plant growth rate and constitutive chemical resistance (foliar cardenolide concentrations), (b) plant growth rate and mechanically induced chemical resistance, (c) constitutive resistance and regrowth tolerance, and (d) regrowth tolerance and mechanically induced resistance. We observed support for one trade-off between plant regrowth tolerance and mechanically induced resistance traits that was, surprisingly, independent of CO2 exposure. Across milkweed species, mechanically induced resistance increased by 28% in those plants previously exposed to elevated CO2. In contrast, constitutive resistance and the diversity of mechanically induced chemical resistance traits declined in response to elevated CO2 in two out of four milkweed species. Finally, previous exposure to elevated CO2 uncoupled the positive relationship between plant growth rate and regrowth tolerance following damage. Our data highlight the complex and dynamic nature of plant defense phenotypes under environmental change and question the generality of physiologically based defense trade-offs.
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Affiliation(s)
| | - Mark D. Hunter
- Department of Ecology and Evolutionary BiologyUniversity of MichiganBiological Sciences BuildingAnn ArborMIUSA
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Tan W, Acevedo T, Harris EV, Alcaide TY, Walters JR, Hunter MD, Gerardo NM, Roode JC. Transcriptomics of monarch butterflies (
Danaus plexippus
) reveals that toxic host plants alter expression of detoxification genes and down‐regulate a small number of immune genes. Mol Ecol 2019; 28:4845-4863. [DOI: 10.1111/mec.15219] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/24/2019] [Accepted: 07/26/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Wen‐Hao Tan
- Department of Biology Emory University Atlanta GA USA
| | - Tarik Acevedo
- Department of Biology Emory University Atlanta GA USA
- Department of Ecosystem Science and Management Pennsylvania State University State College PA USA
| | | | - Tiffanie Y. Alcaide
- Department of Biology Emory University Atlanta GA USA
- Department of Ecosystem Science and Management Pennsylvania State University State College PA USA
| | - James R. Walters
- Department of Ecology and Evolutionary Biology University of Kansas Lawrence KS USA
| | - Mark D. Hunter
- Department of Ecology & Evolutionary Biology University of Michigan Ann Arbor MI USA
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Decker LE, Soule AJ, de Roode JC, Hunter MD. Phytochemical changes in milkweed induced by elevated CO
2
alter wing morphology but not toxin sequestration in monarch butterflies. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13270] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Leslie E. Decker
- Department of Biology Stanford University Stanford California
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
| | - Abrianna J. Soule
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
- Department of Biology University of Utah Salt Lake City Utah
| | | | - Mark D. Hunter
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor Michigan
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