Meeting Abstract

65.4  Friday, Jan. 6  Rates of hybridization, introgression, and formation of chimaeric lineages in Darters. KECK, BP; University of Tennessee

It is currently accepted that hybridization and introgression can influence the evolutionary trajectory of a lineage and affect patterns of diversification. Whether it is the capture of a heterospecific mitochondrial genome or the formation of a chimaeric (or hybrid) lineage with a mosaic genome, the novel combination of genetic material may allow an organism to exploit a novel environment. However, the rates at which hybridization, introgression, and formation of chimaeric lineages occur in nature are not often investigated in a phylogenetic framework. Darters are an excellent group in which to study these rates, because they are one of the most well researched clades of North American freshwater fishes. There are published studies on the number of darter species that hybridize (~25%), that have experienced some extent of introgression (~12.5%), and we have identified at least one chimaeric lineage. Using a recently published phylogenetic hypothesis for 98.8% of darter species that is time calibrated, I examine the timeframe for these events in a phylogenetic context.