Speciation genetics in two pairs of high-latitude, migratory bird taxa

Abstract

I investigated and characterized the divergence of two pairs of putatively young, high-latitude, migratory bird taxa with data from mitochondria) and nuclear DNA. I chose pairs exhibiting natural history attributes suggesting divergence scenarios that probably did not involve strict allopatry. First, I examined Pluvialis dominica and P. fulva, migratory plover species with a largely parapatric breeding range in Beringia. Secondly, I examined Aegolius acadicus acadicus and A. a. brooksi, a subspecies pair of owls where one subspecies (brooksi) is endemic to Haida Gwaii, Canada, a location where subspecies acadicus occurs during migration, resulting in cyclic sympatry (heteropatry) with brooksi. Using mtDNA sequence data and AFLPs I made inferences about population parameters, inferred the likely number of populations, and sought evidence of selection. Gene flow was very low in both pairs. The plovers are much older than was anticipated (1.8 Mybp), although hybridization does occur. Evidence for parapatric or speciation with gene flow scenarios was not found in the plovers, perhaps because the speciation event occurred far in the past. The owl's divergence date was relatively young (~16,000 ybp). Some evidence was found suggesting that heteropatric divergence contributed to the owl's differentiation, although the process could also have reinforced differences acquired largely in allopatry.