The School of Biology welcomes Dr. DeChaine, associate professor at Western Washington University, on "Climatic Variability: The Driver of Diversification, Endemism, and Rarity in Tundra Plants"

Abstract:
The arctic-alpine tundra of western North America harbors a diverse flora, with many rare and endemic taxa. In my lab, we are asking why, when, and where arctic-alpine plants diversified. To address this question, we have taken a comparative molecular approach, employing phylogenetic and population genetic analyses of multiple genetic loci for a taxonomically diverse suite of angiosperms. The topographical and environmental heterogeneity of the region has provided a landscape for geographically structured plant populations. On this stage, the glacial cycles of the Quaternary have played out repeated rounds of population expansion, fragmentation, and isolation, which in turn have promoted genetic divergence and speciation, with the opportunity for local adaptation.

Our studies have revealed colonization events, isolation in and among refugia, recent episodes of diversification, cryptic species, and environmental differences across refugia with the potential for adaptation. Thus, the upshot is that for arctic-alpine plants the Quaternary has promoted speciation. These findings have important implications for the conservation of arctic-alpine plants and the capacity of species to respond to climate change.