熊超科的分子系统发生研究

Molecular Phylogeny of the Superfamily Arctoidea

有关熊超科的系统发生与演化存在很多争议。本工作测定了黑足鼬、南方海狮和非洲猎犬线粒体细胞色素ｂ、１２ＳｒＲＮＡ、ｔＲＮＡｔｈｒ和ｔＲＮＡＰｒｏ基因片段的ＤＮＡ序列。结合我们过去确定的熊超科其他动物的ＤＮＡ序列，我们采用简约法和距离法构建了较为系统的熊超科分子系统树。结果表明：浣熊科与鼬科、熊科与大熊猫科分别具有较近的共同祖先；鳍脚类不是一个独立的目，它们应归入熊超科；鳍脚类可能是单起源的，它们与浣熊科和鼬科的关系较与其他科更紧密；小熊猫科与其他科的关系并不密切。

he Arctoidea is a superfamily of Carnivora that contains eight families:the bears(Ursidae),giant panda(Ailuropodidae),raccoons and allies(Procyonidae),lesser panda(Ailuridae),skunks,otters,weasels,and relatives(Mustelidae),sealions and eared seals(Otariidae),seals(Phocidae),and the walrus(Odobenidae)The phylogenetic relationships among many families are very controversialTo examine different hypotheses on the phylogeny of the Arctoidea,wesequenced segments of mitochondrial cytochrome b and 12S rRNA and tRNA genes from the Southern sealion,the black-footed ferret,and the hunting dogParsimonious analysis based on the transversions of RNA genes,and substitutions at the first and second codon positions and transversions at the third codon position of the cytochrome b gene supports the placement of the Procyonidae with the Mustelidae,and the Ailuropodidae with the UrsidaeOur findings indicates that the Otariidae shares a common ancestor with the Procyonidae and Mustelidae rather than with the UrsidaeOur results do not support the diphyletic origin of the pinnipedsOur findings suggest that the Ailuridae is not closely related to either the Ursidae or the Procyonidae,and may represent an early radiation within the Arctoidea