Temporal congruence revisited: Comparison of mitochondrial DNA sequence divergence in cospeciating pocket gophers and their chewing lice

Molecular phylogenies can be used to test hypotheses of cospeciation between hosts and parasites by comparing both cladistic relationships and branch lengths. Molecular data can also help discriminate between competing reconstructions of the history of the host-parasite association. Methods for comparing sequence divergence in hosts and parasites are described and applied to data for pocket gophers and their chewing lice. The hypothesis of cospeciation between these two clades is strongly supported. The lengths of homologous branches in the gopher and louse phylogenies are positively correlated, but there is little support for the hypothesis that lice are evolving an order of magnitude faster than are their hosts.