Adaptation to environmental change is central to the origin and persistence of species. Mismatches between the timing of key life history events and optimal environmental conditions have emerged as an important threat to biodiversity, yet the evolutionary dynamics of most seasonal adaptations remain poorly understood. We have used extensive museum archives to map geographic clines in the seasonal camouflage of several species against local climatic variables, identifying global regions that are likely to foster rapid evolutionary responses to changing climates. Building on this overarching framework, we have begun to independently dissect the genetic underpinnings of local seasonal adaptation. In the snowshoe hare, we have combined population genomic association mapping of archived field collections with pedigree analyses and functional genomic studies in captive animals to dissect the genetic basis and evolutionary history of alternative winter white or brown pelage morphs. Our results reveal a striking history of gene flow (introgression) between species, which has seeded past and ongoing adaptive responses to seasonal environments. Collectively, these studies provide one the first examples of a clear genotype-to-phenotype-to-fitness link for a seasonally changing trait. These findings yield important insights into how this crucial component of seasonal flexibility may respond to rapid environmental changes in snowshoe hares and other species.
The central goal of my research is to understand the origin of biological diversity. My research program addresses fundamental questions on the origin of species, the genetic basis of ecological adaptation, and the evolution of mammalian reproduction. Focusing primarily on mammalian systems, we combine comparative and population genomic studies with systems genetic analyses of laboratory models to understanding the genetic basis of speciation and adaptation.