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Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus

Endangered species that exist in small isolated populations are at elevated risk of losing adaptive variation due to genetic drift. Analyses that estimate short‐term effective population sizes, characterize historical demographic processes, and project the trajectory of genetic variation into the fu...

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Autores principales: Sovic, Michael, Fries, Anthony, Martin, Scott A., Lisle Gibbs, H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6439488/
https://www.ncbi.nlm.nih.gov/pubmed/30976301
http://dx.doi.org/10.1111/eva.12731
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author Sovic, Michael
Fries, Anthony
Martin, Scott A.
Lisle Gibbs, H.
author_facet Sovic, Michael
Fries, Anthony
Martin, Scott A.
Lisle Gibbs, H.
author_sort Sovic, Michael
collection PubMed
description Endangered species that exist in small isolated populations are at elevated risk of losing adaptive variation due to genetic drift. Analyses that estimate short‐term effective population sizes, characterize historical demographic processes, and project the trajectory of genetic variation into the future are useful for predicting how levels of genetic diversity may change. Here, we use data from two independent types of genetic markers (single nucleotide polymorphisms [SNPs] and microsatellites) to evaluate genetic diversity in 17 populations spanning the geographic range of the endangered eastern massasauga rattlesnake (Sistrurus catenatus). First, we use SNP data to confirm previous reports that these populations exhibit high levels of genetic structure (overall Fst = 0.25). Second, we show that most populations have contemporary Ne estimates <50. Heterozygosity–fitness correlations in these populations provided no evidence for a genetic cost to living in small populations, though these tests may lack power. Third, model‐based demographic analyses of individual populations indicate that all have experienced declines, with the onset of many of these declines occurring over timescales consistent with anthropogenic impacts (<200 years). Finally, forward simulations of the expected loss of variation in relatively large (Ne = 50) and small (Ne = 10) populations indicate they will lose a substantial amount of their current standing neutral variation (63% and 99%, respectively) over the next 100 years. Our results argue that drift has a significant and increasing impact on levels of genetic variation in isolated populations of this snake, and efforts to assess and mitigate associated impacts on adaptive variation should be components of the management of this endangered reptile.
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spelling pubmed-64394882019-04-11 Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus Sovic, Michael Fries, Anthony Martin, Scott A. Lisle Gibbs, H. Evol Appl Original Articles Endangered species that exist in small isolated populations are at elevated risk of losing adaptive variation due to genetic drift. Analyses that estimate short‐term effective population sizes, characterize historical demographic processes, and project the trajectory of genetic variation into the future are useful for predicting how levels of genetic diversity may change. Here, we use data from two independent types of genetic markers (single nucleotide polymorphisms [SNPs] and microsatellites) to evaluate genetic diversity in 17 populations spanning the geographic range of the endangered eastern massasauga rattlesnake (Sistrurus catenatus). First, we use SNP data to confirm previous reports that these populations exhibit high levels of genetic structure (overall Fst = 0.25). Second, we show that most populations have contemporary Ne estimates <50. Heterozygosity–fitness correlations in these populations provided no evidence for a genetic cost to living in small populations, though these tests may lack power. Third, model‐based demographic analyses of individual populations indicate that all have experienced declines, with the onset of many of these declines occurring over timescales consistent with anthropogenic impacts (<200 years). Finally, forward simulations of the expected loss of variation in relatively large (Ne = 50) and small (Ne = 10) populations indicate they will lose a substantial amount of their current standing neutral variation (63% and 99%, respectively) over the next 100 years. Our results argue that drift has a significant and increasing impact on levels of genetic variation in isolated populations of this snake, and efforts to assess and mitigate associated impacts on adaptive variation should be components of the management of this endangered reptile. John Wiley and Sons Inc. 2019-01-28 /pmc/articles/PMC6439488/ /pubmed/30976301 http://dx.doi.org/10.1111/eva.12731 Text en © 2018 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Articles
Sovic, Michael
Fries, Anthony
Martin, Scott A.
Lisle Gibbs, H.
Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title_full Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title_fullStr Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title_full_unstemmed Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title_short Genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, Sistrurus catenatus
title_sort genetic signatures of small effective population sizes and demographic declines in an endangered rattlesnake, sistrurus catenatus
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6439488/
https://www.ncbi.nlm.nih.gov/pubmed/30976301
http://dx.doi.org/10.1111/eva.12731
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