USE OF SPECTRAL-ANALYSIS TO TEST HYPOTHESES ON THE ORIGIN OF PINNIPEDS
USE OF SPECTRAL-ANALYSIS TO TEST HYPOTHESES ON THE ORIGIN OF PINNIPEDS
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DOI：
10.1093/oxfordjournals.molbev.a040189
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发表时间：
1995-01-01
影响因子：
10.7
通讯作者：
PENNY, D
中科院分区：
文献类型：
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作者：
LENTO, GM;HICKSON, RE;PENNY, D
鳍脚类动物(海豹、海狮和海象)的进化起源仍然不确定。大多数作者支持一种假设，即鳍脚类动物起源于犬形食肉动物。一种少数人的观点认为，真正的海豹起源于海豹，与海燕(水獭和雪貂)有亲缘关系。海象与其他羽足动物和食肉动物家族的系统发育关系也仍然存在特别的问题。在这里，我们使用来自线粒体小亚基(12S)rRNA和细胞色素b基因的DNA序列数据来检验对单系和双系假说的相对支持。我们首先分析了一小群代表三个羽足科的分类群(光足科、水龙科和臭虫科)，以及被认为与它们有亲缘关系的犬形食肉动物科。我们使用标准简约算法和邻居连接算法从DNA序列数据中推断系统发育重建，以及一种名为光谱分析(Hendy和Penny)的新方法，在这种方法中，系统发育信息独立于任何选定的树显示。我们识别并补偿了已知的导致错误系统发育树选择的潜在误差源。这些问题包括抽样误差、谱系进化速度不一致、谱系间核苷酸组成不一致、不同地点的变化率不一致以及不适当的树种选择标准。为了纠正这些错误，我们对序列数据中观察到的替换模式进行了额外的转换，对分析应用了更严格的结构约束，并包括了几个额外的分类群，以帮助解决树中长的、未分支的谱系。我们发现，与熊/浣熊/熊猫辐射相近的犬形食肉动物内部，有强烈的支持鳍足类的单系起源。二系起源的证据非常薄弱，可以部分归因于所分析的分类群中不同的核苷酸组成。随后，有更多的证据表明，将海象与海豹和真正的海豹进行归类。然而，一种更保守的解释是，海象是早期的，但不是第一次独立于共同的羽足祖先的分化。
The evolutionary origin of the pinnipeds (seals, sea lions, and walruses) is still uncertain. Most authors support a hypothesis of a monophyletic origin of the pinnipeds from a caniform carnivore. A minority view suggests a diphyletic origin with true seals being related to the mustelids (otters and ferrets). The phylogenetic relationships of the walrus to other pinniped and carnivore families are also still particularly problematic. Here we examined the relative support for mono- and diphyletic hypotheses using DNA sequence data from the mitochondrial small subunit (12S) rRNA and cytochrome b genes. We first analyzed a small group of taxa representing the three pinniped families (Phocidae, Otariidae, and Odobenidae) and caniform carnivore families thought to be related to them. We inferred phylogenetic reconstructions from DNA sequence data using standard parsimony and neighbor-joining algorithms for phylogenetic inference as well as a new method called spectral analysis (Hendy and Penny) in which phylogenetic information is displayed independently of any selected tree. We identified and compensated for potential sources of error known to lead to selection of incorrect phylogenetic trees. These include sampling error, unequal evolutionary rates on lineages, unequal nucleotide composition among lineages, unequal rates of change at different sites, and inappropriate tree selection criteria. To correct for these errors, we performed additional transformations of the observed substitution patterns in the sequence data, applied more stringent structural constraints to the analyses, and included several additional taxa to help resolve long, unbranched lineages in the tree. We find that there is strong support for a monophyletic origin of the pinnipeds from within the caniform carnivores, close to the bear/raccoon/panda radiation. Evidence for a diphyletic origin was very weak and can be partially attributed to unequal nucleotide compositions among the taxa analyzed. Subsequently, there is slightly more evidence for grouping the walrus with the eared seals versus the true seals. A more conservative interpretation, however, is that the walrus is an early, but not the first, independent divergence from the common pinniped ancestor.