Population genetics and historical introgression of a North American passerine within the genus Sialia

Abstract

This study analyzed the genetic structure of mountain bluebirds (Sialia currucoides) from across their range using restriction site-associated DNA sequencing to find single nucleotide polymorphisms. I found evidence of at least four distinct genetic clusters, two of which were in Alberta. I then went on to hypothesize current and historical barriers to gene flow. In the third chapter, I examined the mountain bluebird breeding populations in Alberta and Saskatchewan for signals of current and historical hybridization. Although I did not find evidence of recent hybridization, I did detect signals of ancient introgression from both bluebird congeners. I then used both nuclear and mitochondrial DNA to examine the Sialia polytomy containing all three species of bluebirds. The polytomy showed signs of both incomplete lineage sorting between mitochondrial genes and mitonuclear discordance. As such, it appears that hybridization and other potential factors may obscure the evolutionary history of the entire genus.