Cospeciation of Catharus thrushes and their parasitic chewing lice (Insecta: Phthiraptera)

I tested for cospeciation between Catharus thrushes and their chewing lice by constructing phylogenies for the two genera of lice, Brueelia (Ischnocera) and Myrsidea (Amblycera), and comparing them to a published phylogeny for the thrushes. Lice were collected from five species of North American thrushes captured or collected in Northeastern Illinois in the spring of 2006. I extracted DNA from the lice, amplified and then sequenced three genes: CO1, 12s (mitochondrial), and EF1α (nuclear). I then created a louse phylogeny from these DNA sequences, plus sequences provided by Kevin P. Johnson, using maximum parsimony, maximum likelihood, and Bayesian analyses. Brueelia lice from thrushes do not appear to have speciated, much less cospeciated with their hosts. Myrsidea show a greater degree of diversification than Brueelia, but also do not appear to have cospeciated with thrushes. The lack of differentiation and/or cospeciation suggests that host switching is rampant in this system.