Linking extinction–colonization dynamics to genetic structure in a salamander metapopulation

Abstract

Theory predicts that founder effects have a primary role in determining metapopulation genetic structure. However, ecological factors that affect extinction -colonization dynamics may also create spatial variation in the strength of genetic drift and migration. We tested the hypothesis that ecological factors underlying extinction -colonization dynamics influenced the genetic structure of a tiger salamander (Ambystoma tigrinum) metapopulation. We used empirical data on metapopulation dynamics to make a priori predictions about the effects of population age and ecological factors on genetic diversity and divergence among 41 populations. Metapopulation dynamics of A. tigrinum depended on wetland area, connectivity and presence of predatory fish. We found that newly colonized populations were more genetically differentiated than established populations, suggesting that founder effects influenced genetic structure. However, ecological drivers of metapopulation dynamics were more important than age in predicting genetic structure. Consistent with demographic predictions from metapopulation theory, genetic diversity and divergence depended on wetland area and connectivity. Divergence was greatest in small, isolated wetlands where genetic diversity was low. Our results show that ecological factors underlying metapopulation dynamics can be key determinants of spatial genetic structure, and that habitat area and isolation may mediate the contributions of drift and migration to divergence and evolution in local populations.

Landscape community genomics: understanding eco-evolutionary processes in complex environments

“…Unraveling geographic, ecological, and evolutionary effects on landscape genetics relies on the combination of neutral and non-neutral markers provided by genomics data, as well as on the multi-species and multi-factorial LCG approach (Figure 1). Great advances could be made simply by accounting for community composition in landscape genetic models, allowing local biotic effects to compete with habitat and geographic effects in statistical models [52,53]. Further, it is possible to discern local adaptation (e.g., in a competitive dominant) by comparing patterns of genetic structure of neutral and non-neutral markers, and by testing for patch-specific effects (biotic or abiotic) on genetic structure.…”

Rapid genetic restoration of a keystone species exhibiting delayed demographic response

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“…target effect; Cosentino et al . ). However, dispersal is not a ‘neutral’ trait that depends only on geography (Lowe & McPeek ).…”

“…Whitlock ; Giles & Goudet ; Cosentino et al . ) and (iii) mean genetic diversity should be lower at treated sites than at remnant grasslands due to limited genetic diversity at recently colonized sites.…”

Applying gene flow science to environmental policy needs: a boundary work perspective

“…The combined demographic and genetic effects of migration and gene flow can ensure the existence of populations that would otherwise fail to be self‐sustaining (Lenormand ; Cosentino et al. ; Mushet et al. ).…”