Su B, Wang Y X, Lan H, Wang W, Zhang Y
Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Peoples Republic of China.
Mol Phylogenet Evol. 1999 Aug;12(3):241-9. doi: 10.1006/mpev.1999.0616.
As an endangered animal group, musk deer (genus Moschus) are not only a great concern of wildlife conservation, but also of special interest to evolutionary studies due to long-standing arguments on the taxonomic and phylogenetic associations in this group. Using museum samples, we sequenced complete mitochondrial cytochrome b genes (1140 bp) of all suggested species of musk deer in order to reconstruct their phylogenetic history through molecular information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum likelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting the dating of divergence events by molecular clock. According to the molecular topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation forming the M. berezovskii lineage and the lineage clustering M. fuscus, M. chrysogaster, and M. leucogaster (around 370,000 years before present). Interestingly, the most recent speciation event in musk deer happened rather recently (140,000 years ago), which might have resulted from the diversified habitats and geographic barriers in southwest China caused by gigantic movements of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we suggest that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora species, musk deer was strongly supported as a monophyletic group and a valid family in Artiodactyla, closely related to Cervidae.
作为一个濒危动物群体，麝（麝属）不仅是野生动物保护的重点关注对象，而且由于该群体在分类学和系统发育关联方面长期存在争议，对进化研究也具有特殊意义。我们利用博物馆标本，对所有已提出的麝种的线粒体细胞色素b基因全长（1140 bp）进行了测序，以便通过分子信息重建它们的系统发育历史。我们的结果表明，细胞色素b基因树相当稳健，并且在所有使用的算法（简约法、最大似然法和距离法）中都一致。此外，相对速率检验表明所有物种之间的序列替代率恒定，这使得可以通过分子钟对分歧事件进行年代测定。根据分子拓扑结构，原麝最早从麝的共同祖先中分支出来（约70万年前）；接着是形成黑麝谱系以及将林麝、马麝和白腹麝聚类的谱系的分支（距今约37万年前）。有趣的是，麝的最近一次物种形成事件发生在相当近的时期（14万年前），这可能是由于历史上青藏高原的巨大运动导致中国西南部栖息地多样化和地理屏障造成的。结合本研究的当前分布数据、化石记录和分子数据，我们认为麝在中国的历史扩散可能是由北向南的。此外，在我们涉及其他偶蹄目物种的进一步分析中，麝被强烈支持为一个单系群，并且是偶蹄目中一个有效的科，与鹿科关系密切。
