Phylogenetic study of complete cytochrome b genes in musk deer (genus Moschus) using museum samples

As an endangered animal group, musk deer (genus Moschus) are not only a gre at concern of wildlife conservation, but also of special interest to evolut ionary studies due to long-standing arguments on the taxonomic and phylogen etic associations in this group. Using museum samples, we sequenced complet e mitochondrial cytochrome b genes (1140 bp) of all suggested species of mu sk deer in order to reconstruct their phylogenetic history through molecula r information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum l ikelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting th e dating of divergence events by molecular clock. According to the molecula r topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation form ing the M. berezouskii lineage and the lineage clustering M. fuscus, M. chr ysogaster, and M. leucogaster (around 370,000 years before present), intere stingly the most recent speciation event in musk deer happened rather recen tly (140,000 years ago), which might have resulted from the diversified hab itats and geographic barriers in southwest China caused by gigantic movemen ts of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we sugges t that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora spec ies, musk deer was strongly supported as a monophyletic group and a valid f amily in Artiodactyla, closely related to Cervidae. (C) 1999 Academic Press .