Tests of the predictability of population genetic structure and change in wild animal populations

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Evolution is the result of changes in the genetic composition of populations through time. Many of the processes that cause population genetic change are intimately tied to ecological conditions. For example, environmental variation causes populations to drift apart genetically if it impedes movement and can cause populations to diverge adaptively if different traits are selected in different environments. Thus, understanding how ecology produces population genetic change is central to understanding evolutionary patterns in nature. My research integrates population genomics with evolutionary ecology to explain the ways that population genetic structures form, persist, collapse, and change through time. I willuse the colonisations of cities by grey squirrels (Sciurus carolinensis) to address my questions. Urbanisation fragments populations, shapes dispersal patterns, alters selective pressures, and is replicated in space. This makes the colonisation of cities by grey squirrels an ideal setting to study contemporary evolution. ***This Discovery Grant cycle I will address questions about the early stages of the process of adaptive population divergence. I will explore: 1) the predictability of selection on genetic variants; 2) whether, and by how much, populations can diverge while interbreeding with differently adapted populations; and 3) whether high recombination rates near putatively selected loci increase the efficiency of selection in new environments by exposing new gene combinations to selection.***Addressing these questions will require integrated analyses of genome-wide molecular markers, whole genome analyses, and intensive field based ecological study. Thus, my program will train highly qualified personnel in bioinformatics, statistical population genetics, population ecology, and field monitoring skills. We will sample squirrels from paired city-forest sites to quantify parallel selection, identify candidate loci for urban adaptation, and model the demographics of divergence. We will use data from intensive fieldwork at a focal site to model survival and reproduction contingent upon environments and genotypes. Then, with whole genome resequencing of individuals from this focal site we will test whether high recombination rates near candidate loci facilitate local adaptation.***By studying contemporary evolutionary change we will learn about the early stages of population divergence. Due to the extensive and accelerating effects of human activities on natural environments this research will also be important for conservation and management science. Urban land cover is predicted to triple between 2000 and 2030. Given the expansion and persistence of cities, understanding the evolutionary effects of urbanisation on natural populations will be important for planning to minimise the negative effects of human activities on natural populations.**