Losos Jonathan B, Irschick Duncan J, Schoener Thomas W
Department of Biology, Campus Box 1137, Washington University, St. Louis, Missouri, 63130-4899.
Section of Evolution and Ecology and Center for Population Biology, Storer Hall, University of California, Davis, California, 95616.
Evolution. 1994 Dec;48(6):1786-1798. doi: 10.1111/j.1558-5646.1994.tb02214.x.
Interspecific interactions affect habitat use and subsequent morphological adaptation in Anolis lizards. We examined populations of two species of Anolis lizards that evolved in the species-rich communities of Cuba and are now widespread in the Bahamas. Because the species occupy islands in the Bahamas that vary in the number of lizard species present and other characteristics, we predicted that directional selection should have led to morphological differentiation. In particular, we expected that populations on one-species islands should have evolved toward a generalist morphology because of the lack of competitors. Divergence in both species has been adaptive; populations that use wider perches have longer legs. Nonetheless, these differences are relatively minor, and none of the populations appears to have differentiated from its ancestral "ecomorph" type toward a more generalized morphology. This stasis mirrors a trend observed in the radiation of Caribbean anoles, which exhibits repeated instances of evolutionary specialization, but few or no cases of reversion to a more generalized condition. The explanation for this directionality of evolution is not obvious but probably involves the tendency of specialized species to continue using and further adapting the niches for which they are specialized even as conditions change.
种间相互作用影响安乐蜥的栖息地利用及随后的形态适应。我们研究了两种安乐蜥的种群，它们在物种丰富的古巴群落中进化，现在广泛分布于巴哈马群岛。由于这些物种占据的巴哈马群岛上蜥蜴物种数量及其他特征各不相同，我们预测定向选择应该导致了形态分化。特别是，我们预计单物种岛屿上的种群应该已经朝着通才形态进化，因为缺乏竞争者。两个物种的分化都是适应性的；使用更宽栖木的种群腿更长。然而，这些差异相对较小，而且没有一个种群似乎已经从其祖先的“生态形态”类型分化为更一般化的形态。这种停滞反映了在加勒比安乐蜥辐射中观察到的一种趋势，即进化特化反复出现，但很少或没有恢复到更一般化状态的情况。进化这种方向性的解释并不明显，但可能涉及即使环境变化，特化物种仍倾向于继续利用并进一步适应它们所特化的生态位的趋势。
