Systematics of grouse and ptarmigan determined by nucleotide sequences of the mitochondrial cytochrome-B gene

The delineation of species groups and determination of relationships among taxa within the Tetraoninae (grouse and ptarmigan) have relied heavily on anatomical and behavioral specializations associated with reproduction. As a result, the various classifications of tetraonines differ considerably with respect to the phylogenetic relationships depicted for the primary species groups. We used nucleotide sequence data derived from the mitochondrial cytochrome-b gene to examine relationships among all New World taxa and the major Old World ''superspecies'' groups of grouse and ptarmigan. The cytochrome-b sequence data: (1) indicated an early divergence of the Bonasa species; (2) grouped Dendragapus obscurus with Tympanuchus and supported an association of these taxa with Lagopus and Tetrao; and (3) suggested that tetraonines underwent a period of rapid diversification in North America. The molecular phylogeny provides support for adaptive interpretations of morphological and behavioral variation among grouse and ptarmigan and indicates that the complex reproductive systems of tetraonines reflect homoplasy probably as a result of convergent evolution. We recommend that grouse and ptarmigan taxonomy incorporate genetic considerations and that classifications reflect common ancestry.