A DIFFERENT TEMPO OF MITOCHONDRIAL-DNA EVOLUTION IN BIRDS AND THEIR PARASITIC LICE

A phylogeny for the Lice (Insecta: Phthiraptera: genus Dennyus) parasi tic on swiftlets (Aves: Collocalliinae) was constructed based on mitoc hondrial cytochrome b DNA sequences. This phylogeny is congruent with previous phenetic analyses of morphometric data for the lice. Comparis on with a previously obtained phylogeny for the hosts indicates some d egree of cospeciation. These cospeciation events are used to compare r elative rates of evolution in the birds and their lice for the same se gment of the cytochrome b gene. Cytochrome b is evolving two to three times more rapidly in lice than in birds, and louse cytochrome b is hi ghly divergent compared to that of most other insects. Although genera tion time has been suggested as an explanation for the disparity in ev olutionary rates between Lice and their hosts, we suggest that the sma ll effective population sizes of lice coupled with founder events occu rring during transmission to new host individuals may be an important factor. (C) 1998 Academic Press.