How spatio-temporal habitat connectivity affects amphibian genetic structure

Watts, Alexander; Schlichting, Peter E.; Billerman, Shawn M.; Jesmer, Brett R.; Micheletti, Steven J.; Fortin, Marie-José; Funk, W. Chris; Hapeman, Paul; Muths, Erin; Murphy, Melanie A.

doi:10.3389/fgene.2015.00275

Cited by 65 publications

(58 citation statements)

References 68 publications

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“…, Watts et al. ). In laboratory trials, individual amphibians of the same species from geographically isolated populations have demonstrated differential susceptibility to chytridiomycosis (Murphy et al.…”

Section: Introductionmentioning

confidence: 99%

Host–pathogen metapopulation dynamics suggest high elevation refugia for boreal toads

Mosher

Bailey

Muths

et al. 2018

Ecological Applications

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Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situ disease management. Declines of boreal toads (Anaxyrus boreas boreas) in the southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic data set, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be suboptimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bd systems. Our data suggest that in the southern Rocky Mountains high elevation sites should be prioritized for conservation initiatives like reintroductions.

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Section: Introductionmentioning

confidence: 99%

Host–pathogen metapopulation dynamics suggest high elevation refugia for boreal toads

Mosher

Bailey

Muths

et al. 2018

Ecological Applications

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“…) and dictates moisture levels in summer, affecting connectivity between chorus frog habitats (Watts et al. ). Reduced snowpack (i.e., earlier melt‐out) can result in longer activity seasons for amphibians (McCaffery and Maxell ) but also in an increased number of days of frost and lower soil temperatures (Wipf et al.…”

Section: Discussionmentioning

confidence: 99%

“…), and reduce genetic connectivity among chorus frog populations because of reduced moisture (Watts et al. ).…”

Section: Introductionmentioning

confidence: 99%

Twenty‐nine years of population dynamics in a small‐bodied montane amphibian

et al. 2018

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Identifying population declines before they reach crisis proportions is imperative given the current global decline in vertebrate fauna and associated challenges and expense of recovery. Understanding life histories and how the environment influences demography are critical aspects of this challenge, as is determining the biological relevance of covariates that are best supported by the data. We used 29 yr of data on chorus frogs at two sites to estimate demographic parameters, examine life history, assess weather‐related covariates, and determine the magnitude of process variation in target parameters. Average estimates of survival probabilities were 0.51 (Standard Error [SE] = 0.04) and 0.43 (SE = 0.04), and average estimates of recruitment probabilities were 0.64 (SE = 0.07) and 0.44 (SE = 0.04). Process variation accounted for ≥76% of the total temporal variation in both parameters at one pond and in survival probability alone at the other, suggesting that the covariates in our top models were explaining predominantly process rather than sampling variation. Estimates of population growth rates indicated a declining population at one pond (i.e., negative population growth rates in 15 of 18 yr), and comparisons with historical estimates suggested declines in survival probability at the other. The amount of deviance explained was low, providing little support for the influence of covariates on target parameters, despite model selection support. Synthesis and applications: This analysis illustrates the value of disentangling components of variance when assessing demographic drivers and highlights the need for adequate demographic information in assigning conservation labels.

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“…; Wang ; Wang & Bradburd ; Watts et al . ). Generalized dissimilarity modelling (GDM) can be used to assess the effect of dissimilar habitat on biological data between populations (Ferrier et al .…”

Section: Introductionmentioning

confidence: 97%

An approach for identifying cryptic barriers to gene flow that limit species' geographic ranges

Micheletti

Storfer

2016

Molecular Ecology

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Species' geographic range limits are most often not demarcated by obvious dispersal barriers. Poor-quality habitat at the edge of a species' range can prevent range expansion by preventing outward migration or through reducing adaptive potential resulting from decreased genetic diversity. We identified habitat variables that constrain gene flow across the entire geographic range of an endemic salamander (Ambystoma barbouri) in the eastern United States, and we tested whether increased resistance resulting from these variables provides cryptic dispersal barriers at the range edges. Using polymorphic microsatellite loci, we first identified three genetic clusters that are separated by the Ohio and Kentucky rivers. Through a combination of landscape genetic analyses and generalized dissimilarity modelling, we then classified variables that (i) restrict gene flow in each of the genetic clusters across the geographic distribution of A. barbouri and (ii) become more common towards the peripheries of the distribution. A decrease in limestone availability and an increase in growing season precipitation were correlated with high resistance to gene flow across the range, and both became more common at the edges of the species' distribution. However, other landscape variables were more important for explaining variation in geneflow rates in different portions of the range, such as increased mean annual temperature and frost-free period in the south vs. growing season precipitation in the north. Taken together, these results suggest that there are both range-wide and regionally specific cryptic habitat barriers preventing geographic range expansion. Species 'geographic range limits are probably governed by a set of ecological and evolutionary factors, and our landscape genetic approach could be applied to gain additional insight into many systems.

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How spatio-temporal habitat connectivity affects amphibian genetic structure

Cited by 65 publications

References 68 publications

Host–pathogen metapopulation dynamics suggest high elevation refugia for boreal toads

Host–pathogen metapopulation dynamics suggest high elevation refugia for boreal toads

Twenty‐nine years of population dynamics in a small‐bodied montane amphibian

An approach for identifying cryptic barriers to gene flow that limit species' geographic ranges

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