IS THE GUINEA-PIG A RODENT
IS THE GUINEA-PIG A RODENT
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DOI：
10.1038/351649a0
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发表时间：
1991-06-20
期刊：
影响因子：
64.8
通讯作者：
LI, WH
中科院分区：
文献类型：
--
作者：
GRAUR, D;HIDE, WA;LI, WH
豚鼠（Cavia porcellus），传统上被归类为新大陆的一种hystricomorph啮齿动物，与其他真兽目哺乳动物相比，经常表现出异常的形态和分子特征1-14。例如，它的胰岛素不同于其他哺乳动物的合成代谢和促进生长的活动，并在其能力，形成六聚体5，6。事实上，关于豚鼠分子进化的文献中有很多关于“趋同进化”、“极快的替代率”和“独特的进化机制”的说法。这些说法是基于豚鼠是啮齿动物的假设。然而，我们的氨基酸序列数据的系统发育分析表明，在灵长类动物和偶蹄类动物从肌型啮齿动物（大鼠和小鼠）分离之前，豚鼠就已经分化了。如果是真的，那么肌形目和腔形目并不构成一个自然的分支，腔形目（或组织形目）应该在分类学上被提升，并被视为一个独立的哺乳动物目，与啮齿目不同。如果，如最近的数据15，16所示，肌型动物在食肉动物、兔形目动物、偶蹄类动物和灵长类动物之间的分歧之前就分支了，那么新的目的将代表真兽目辐射的早期分歧。
THE guinea-pig (Cavia porcellus), traditionally classified as a New World hystricomorph rodent, often shows anomalous morphological and molecular features in comparison with other eutherian mammals 1-14. For example, its insulin differs from that of other mammals in anabolic and growth-promoting activities and in its capability to form hexamers 5, 6. Indeed, the literature about the molecular evolution of guinea-pigs abounds in references to 'convergent evolution', 'extremely rapid rates of substitution', and 'unique evolutionary mechanisms'. These claims are based on the assumption that the guinea-pig is a rodent. Our phylogenetic analyses of amino-acid sequence data, however, imply that the guinea-pig diverged before the separation of the primates and the artiodactyls from the myomorph rodents (rats and mice). If true, then the myomorphs and the caviomorphs do not constitute a natural clade, and the Caviomorpha (or the Histricomorpha) should be elevated in taxonomical rank and regarded as a separate mammalian order distinct from the Rodentia. If, as suggested by recent data 15, 16, the myomorphs branched off before the divergence among the carnivores, lagomorphs, artiodactyls and primates, then the new order would represent an early divergence in eutherian radiation.