Multiple molecular evidences for a living mammalian fossil
Multiple molecular evidences for a living mammalian fossil
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DOI：
10.1073/pnas.0701289104
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发表时间：
2007-05-01
影响因子：
11.1
通讯作者：
Schmitz, Juergen
中科院分区：
文献类型：
--
作者：
Huchon, Dorothee;Chevret, Pascale;Schmitz, Juergen
Laonastes aenigmamus是一种神秘的啮齿动物，于2005年首次被描述。分子和形态学数据表明，它是一个新的哺乳动物家族的唯一代表，Laonastidae，和Hystricognathi的成员。然而，这个科的有效性是有争议的，因为基于化石的系统发育分析表明，Laonastes是硅藻科的幸存成员，该科被认为已经灭绝了1100万年。根据这些数据，Laonastes和Diatomyidae是现存的Cteenacytylidae的姐妹分支（即，而不属于Hystricognathi。为了解决Laonastes的系统发育位置，我们进行了大规模的啮齿动物分子系统发育。该分析包括所有主要啮齿动物分类组的代表，并基于来自四个核基因和两个线粒体基因的5.5 kb序列数据。为了进一步验证所获得的结果，还进行了包括11个信息位点的短散布元件插入分析。我们的分子数据的基础上的序列和短散布元素分析明确地放置Laonastes作为一个姐妹枝的gundies。基于Shimodaira-Hasegawa检验，所有替代假设均被显著拒绝，支持Laonastes不属于Hystricognathi的观点。分子测年分析也支持一个古老的分歧，大约44万年前，Cteenacytylidae和Laonastes之间。这些综合分析支持了Laonastes确实是活化石的假设。保护这个幸存的物种将保护一个古老的哺乳动物家族。
Laonastes aenigmamus is an enigmatic rodent first described in 2005. Molecular and morphological data suggested that it is the sole representative of a new mammalian family, the Laonastidae, and a member of the Hystricognathi. However, the validity of this family is controversial because fossil-based phylogenetic analyses suggest that Laonastes is a surviving member of the Diatomyidae, a family considered to have been extinct for 11 million years. According to these data, Laonastes and Diatomyidae are the sister clade of extant Ctenodactylidae (i.e., gundies) and do not belong to the Hystricognathi. To solve the phylogenetic position of Laonastes, we conducted a large-scale molecular phylogeny of rodents. The analysis includes representatives of all major rodent taxonomic groups and was based on 5.5 kb of sequence data from four nuclear and two mitochondrial genes. To further validate the obtained results, a short interspersed element insertion analysis including 11 informative loci was also performed. Our molecular data based on sequence and short interspersed element analyses unambiguously placed Laonastes as a sister clade of gundies. All alternative hypotheses were significantly rejected based on Shimodaira-Hasegawa tests, supporting the idea that Laonastes does not belong to the Hystricognathi. Molecular dating analysis also supports an ancient divergence, approximate to 44 Mya ago, between Ctenodactylidae and Laonastes. These combined analyses support the hypothesis that Laonastes is indeed a living fossil. Protection of this surviving species would conserve an ancient mammalian family.