Tuesday, February 21, 2017 at 10:00am
NSF Postdoctoral Associate
Florida Museum of Natural History, University of Florida
“Hybridization and Diversification: Extreme Phylogenomic Discord in Heuchera”
Abstract: Among the major goals of biodiversity researchers is to assess the drivers behind present-day species-level diversity. Particularly of interest is the relative importance of pathways to diversification, among which hybridization has recently been the subject of intense interest. Recent progress in sequencing technology has facilitated the collection of robust samples of genomic histories (gene genealogies), creating a powerful tool to investigate phylogenomic discord and particularly to detect ancestral hybridization. I have used phylogenomic tools and the multispecies coalescent model to detect hybridization (particularly introgression) at a variety of ages and ploidal levels in the Heuchera system (Saxifragaceae). In recent work developing methods for ancestral reconstruction of habitat suitability, I show that an instance of introgression, where the donor and recipient are currently geographically disjunct by more than 1000 km, was facilitated by climatic cooling during the Pleistocene, during which they were likely parapatrically distributed. Many comparable systems for investigating hybridization contain nascent lineages, with the result that they speak more to the immediate selective pressures and population processes that hybridization causes than to the long-term trajectories of hybrid lineages. Advocating a time-extended, comparative view of reticulate evolution, I argue for the need to develop evolutionary systems containing ancestral hybrids (hybridization followed by cladogenic events) to adequately investigate the impact of hybridization on the tree of life.