Lampreys adjust, mammals non-plussed, birds robust: how ecological and environmental features influence genetic diversity
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Date
2021-12
Authors
Mahoney, Meghan
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Abstract
Evolutionary forces are intrinsically tied to environments and ecosystems species occupy. Gene flow is shaped by conduits and impediments in landscape features and conditions, and spatially separate populations often divergently adapt to heterogenous environments. Understanding the nexus of environments and genetic diversity is vital when managing species, especially in the context of rapid global climate change and increasing anthropogenic disturbance. I used two avenues of study to explore this relationship on large spatial scales. I analyzed whole-genome sequencing data for 209 invasive sea lampreys in the Laurentian Great Lakes, and publicly archived, raw microsatellite data from 1,008 bird and mammal population data points across Canada and the United States. For the former, I hypothesized that as an invasive species recently introduced to a novel environmental gradient, the sea lamprey populations would be locally adapted to conditions in the Great Lakes. For the latter, I hypothesized that the human footprint index (HFI), when used as a resistance surface, would best explain genetic distances in bird and mammal populations in North America. For both studies, I used statistical approaches to look for patterns of genetic diversity among and across populations of animals and identify environmental covariates of these patterns. I found evidence of local adaptation in sea lamprey populations, whereby the adaptive divergence of populations significantly correlated with levels of human population density. Bird and mammal populations were also shaped by human influence, with a positive and negative effect, respectively, of the HFI on genetic distance. Though direction and degree of effects on genetic diversity varied across taxonomic groups, these results indicate the overarching influence environmental variables—particularly, human disturbances—have on spatial distribution and genetic diversity across taxonomic groups. Be it an invasive species, or species of conservation concern, understanding the link between environmental gradients and genetic diversity of animal populations is of both biological and managerial interest.
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Keywords
Genomics, Lamprey, Synthesis, Local adaptation, Isolation-by-environment