Phylogenetics of Perissodactyla and tests of the molecular clock
Phylogenetics of Perissodactyla and tests of the molecular clock
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DOI：
10.1007/s002399910002
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发表时间：
2000-01-01
影响因子：
3.9
通讯作者：
Ashley, MV
中科院分区：
文献类型：
--
作者：
Norman, JE;Ashley, MV
两个线粒体基因，编码蛋白质的细胞色素c氧化酶亚基II（COII）基因和12 S rRNA基因的一部分，用于哺乳动物奇蹄目的系统发育调查。这项研究的主要目的是利用大量的奇蹄目化石记录来校准分子钟，并使用基因和两个化石校准点来比较分歧时间的估计。次要目的包括澄清以前未解决的关系内Tapiridae和比较的结果，单独和合并分析的两个基因。分析包括代表所有三个家庭（Tapiridae，Equidae和Rhinocerotidae），最现存的属，所有四种貘，两到四种犀牛和两种马的几个奇蹄目谱系。一个相对较新的化石校准点和一个相对古老的校准点的应用产生了很大的不同的估计两个基因的进化速率和分歧时间，即使相对速率测试没有发现分类群之间的显着差异率。然而，似然比测试拒绝了这两个基因的分子钟。无论是校准点产生的分歧时间的估计与古生物学证据在一系列的奇蹄类辐射。这两个基因的综合分析产生了一个很好的解决与奇蹄目，符合传统的观点，家族间的关系，并支持新热带区貘单系性。结合数据集增加了对大多数节点的支持，但减少了对新热带区貘分支的支持，因为COII和12S rRNA数据集对貘关系有冲突。
Two mitochondrial genes, the protein-coding cytochrome c oxidase subunit II (COII) gene and a portion of the 12S rRNA gene, were used for phylogenetic investigation of the mammalian order Perissodactyla. The primary objective of the study was to utilize the extensive fossil record of perissodactyls for calibrating molecular clocks and comparing estimates of divergence times using both genes and two fossil calibration points. Secondary objectives included clarification of previously unresolved relationships within Tapiridae and comparison of the results of separate and combined analyses of two genes. Analyses included several perissodactyl lineages representing all three families (Tapiridae, Equidae, and Rhinocerotidae), most extant genera, all four species of tapirs, two to four species of rhinoceros, and two species of Equus. The application of a relatively recent fossil calibration point and a relatively ancient calibration point produced greatly different estimates of evolutionary rates and divergence times for both genes, even though a relative rates test did not find significant rate differences among taxa. A likelihood-ratio test, however, rejected a molecular clock for both genes. Neither calibration point produced estimates of divergence times consistent with paleontological evidence over a range of perissodactyl radiations. The combined analysis of both genes produces a well-resolved phylogeny with Perissodactyla that conforms to traditional views of interfamilial relationships and supports monophyly of neotropical tapirs. Combining the data sets increases support for most nodes but decreases the support for a neotropical tapir clade because the COII and 12S rRNA data sets are in conflict for tapir relationships.