Yonezawa Takahiro, Kohno Naoki, Hasegawa Masami
School of Life Sciences, Fudan University, 220 Han Dan Road, Shanghai, 200433, China.
Gene. 2009 Jul 15;441(1-2):89-99. doi: 10.1016/j.gene.2009.01.022. Epub 2009 Feb 27.
The pinniped family Otariidae (sea lions and fur seals) is composed of 7 extant genera with 14 species. They are mainly distributed in the Southern Hemisphere, but the fossil record is only known from the Northern Hemisphere until Pliocene. To clarify the biological and zoogeographical events during their evolution, it is necessary to reconstruct a robust phylogenetic tree. However, phylogenetic relationships among otariids continue to be controversial, except for the basal position of the northern fur seal among the extant otariids. We reconstructed phylogenetic trees of otariids based on mitochondrial genomes and multiple nuclear genes (IRBP and type I STS markers). The monophyly of the otariids including both sea lions and fur seals in the Southern Hemisphere was strongly supported by both the mitochondrial and nuclear evidence. We propose a novel evolutionary and dispersal scenario of otariids based on this phylogenetic hypothesis, estimated divergence times, and fossil records. According to our results, the center of origin of the southern otariids is hypothesized to be the eastern South Pacific along the west coast of South America.
海狗科（海狮和海狗）由7个现存属和14个物种组成。它们主要分布在南半球，但直到上新世，化石记录仅来自北半球。为了阐明它们进化过程中的生物学和动物地理学事件，有必要构建一个可靠的系统发育树。然而，除了北海狗在现存海狗科中的基部位置外，海狗科之间的系统发育关系仍然存在争议。我们基于线粒体基因组和多个核基因（视黄醇结合蛋白和I型STS标记）重建了海狗科的系统发育树。线粒体和核证据都强烈支持包括南半球海狮和海狗在内的海狗科的单系性。我们基于这个系统发育假说、估计的分歧时间和化石记录，提出了一种新的海狗科进化和扩散模式。根据我们的结果，推测南部海狗科的起源中心是南美洲西海岸沿线的东太平洋。
