Center for Tropical Research, Institute of the Environment, University of California, Los Angeles, CA 90095-1496, USA.
J Evol Biol. 2012 Mar;25(3):509-21. doi: 10.1111/j.1420-9101.2011.02447.x. Epub 2012 Jan 13.
The faunas associated with oceanic islands provide exceptional examples with which to examine the dispersal abilities of different taxa and test the relative contribution of selective and neutral processes in evolution. We examine the patterns of recent differentiation and the relative roles of gene flow and selection in genetic and morphological variation in the yellow warbler (Dendroica petechia aureola) from the Galápagos and Cocos Islands. Our analyses suggest aureola diverged from Central American lineages colonizing the Galápagos and Cocos Islands recently, likely less than 300 000 years ago. Within the Galápagos, patterns of genetic variation in microsatellite and mitochondrial markers suggest early stages of diversification. No intra-island patterns of morphological variation were found, even across steep ecological gradients, suggesting that either (i) high levels of gene flow may be homogenizing the effects of selection, (ii) populations may not have had enough time to accumulate the differences in morphological traits, or (iii) yellow warblers show lower levels of 'evolvability' than some other Galápagos species. By examining genetic data and morphological variation, our results provide new insight into the microevolutionary processes driving the patterns of variation.
与海洋岛屿相关的动物群为我们提供了极好的例子，可以用它们来检验不同分类群的扩散能力，并检验选择和中性过程在进化中的相对贡献。我们研究了加拉帕戈斯群岛和可可斯群岛的黄莺（Dendroica petechia aureola）最近的分化模式，以及基因流和选择在遗传和形态变异中的相对作用。我们的分析表明，aureola 与最近殖民加拉帕戈斯群岛和可可斯群岛的中美洲谱系分化，可能不到 30 万年。在加拉帕戈斯群岛，微卫星和线粒体标记的遗传变异模式表明了早期的多样化阶段。即使在陡峭的生态梯度上，也没有发现岛屿内的形态变异模式，这表明（i）高水平的基因流可能使选择的影响均匀化，（ii）种群可能没有足够的时间积累形态特征的差异，或者（iii）黄莺的“可进化性”水平低于其他一些加拉帕戈斯物种。通过检查遗传数据和形态变异，我们的结果为驱动变异模式的微观进化过程提供了新的见解。
