Tague Robert G
Department of Geography and Anthropology, Louisiana State University, Baton Rouge, Louisiana, 70803-4105.
Evolution. 1997 Apr;51(2):595-605. doi: 10.1111/j.1558-5646.1997.tb02446.x.
A tenet of evolutionary theory is that, under conditions of stabilizing selection, phenotypic variability is inversely related to selection intensity. Correspondingly, a nonfunctional, vestigial structure is expected to be highly variable relative to its functional homologue. This study tests the hypothesis that species with a vestigial pollex, Colobus guereza and Ateles geoffroyi, have a first metacarpal whose length is both highly variable relative to, and poorly correlated with, the lengths of the other metapodials. The results are consistent with the hypothesis, though this combination of traits is also found in Presbytis rubicunda and Presbytis cristata. The latter two species have functional, albeit miniature, pollices. This study also demonstrates a general, inverse relationship among anthropoid primates between relative length of the first metapodial and its relative variability. These results suggest that elevated variability accompanies structural reduction.
进化理论的一个原则是，在稳定选择的条件下，表型变异性与选择强度呈负相关。相应地，一个无功能的残留结构相对于其功能同源物预期具有高度变异性。本研究检验了这样一个假设，即疣猴和蜘蛛猴这两种具有残留拇指的物种，其第一掌骨的长度相对于其他掌骨的长度而言，既具有高度变异性，又与其相关性较差。结果与该假设一致，不过在红毛叶猴和冠叶猴中也发现了这种性状组合。后两个物种具有功能性的拇指，尽管很小。本研究还证明了在类人猿灵长类动物中，第一掌骨的相对长度与其相对变异性之间存在普遍的负相关关系。这些结果表明，结构简化伴随着变异性的增加。
