Causes and consequences of hybridization in mammals

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The rapid pace of contemporary climate change means that we may be entering an era of intense natural selection. Interspecific hybridization is often considered to be a consequence of climate change, but it is also potentially an important mechanism of rapid adaptation. This is because hybridization is a relatively fast way to arrive at new combinations of genes, which may then produce novel traits in organisms. Under appropriate environmental conditions, these novel traits may persist in the population if they confer a fitness advantage.******My research program involves testing hypotheses about the causes and consequences of hybridization in mammals. My colleagues and I have observed hybridization between the northern and southern flying squirrel in a secondary contact zone that has recently emerged between these species in Ontario due to range expansion by the southern species. We will use long-term survey data of the southern flying squirrel to test whether climate change is an important cause of range expansion, and therefore hybridization with the northern species. We will also test two hypotheses explaining the observed pattern of hybridization: the absence of evolved reproductive barriers due to a lack of any historic spatial overlap, and the effects of parasite-mediated competition between flying squirrel species. We will use the patterns of gene flow observed in squirrel genomes to test these causes of hybridization. We will also carry out studies to evaluate some consequences of hybridization. In particular, we are interested in effects of hybridization on acoustic signals and on the fungus-eating habits of the northern flying squirrel, which can aid in forest regeneration. The northern flying squirrel deposits fungal spores and nitrogen-fixing bacteria in the soil, which can be important for tree growth in nitrogen-limited forests.**