Harmon Luke J, Gibson Richard
Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
Evolution. 2006 Dec;60(12):2622-32.
Interpopulation variation in morphology, such as that among small island populations, plays a key role in speciation and diversification. There are two approaches to investigating evolution of morphological characters: comparing patterns of trait variances and covariances within and among populations, and testing particular adaptive scenarios. Here, we combine both approaches to infer the role of natural selection in shaping morphological variation in body size, head color pattern, and body shape among 10 populations of a day gecko, Phelsuma ornata, and its close relative, P. inexpectata, in the Mascarene Islands. We find that local populations are morphologically distinct, and that natural selection has likely influenced phenotypic diversification in the group. Lizards on small outer islands tend to be larger than lizards on the mainland of Mauritius. For body shape and head color pattern, comparisons of variation within and among populations reveal that differences among populations for some variables are too great to be explained by neutral processes alone, although we cannot identify the causal agents for this selection. These results reveal that the forces shaping different sets of organismal traits may be distinct, such that a variety of statistical approaches are needed to investigate selection in natural populations.
种群间的形态差异，比如小岛屿种群之间的差异，在物种形成和多样化过程中起着关键作用。研究形态特征进化有两种方法：比较种群内部和种群之间的性状方差和协方差模式，以及检验特定的适应性情景。在这里，我们结合这两种方法，来推断自然选择在塑造马埃岛日行壁虎（Phelsuma ornata）及其近亲意外日行壁虎（P. inexpectata）的10个种群的体型、头部颜色模式和身体形状的形态变异中所起的作用。我们发现当地种群在形态上是不同的，并且自然选择可能影响了该类群的表型多样化。小外岛上的蜥蜴往往比毛里求斯大陆上的蜥蜴更大。对于身体形状和头部颜色模式，种群内部和种群之间的变异比较表明，某些变量在种群之间的差异太大，无法仅用中性过程来解释，尽管我们无法确定这种选择的因果因素。这些结果表明，塑造不同生物体性状组的力量可能是不同的，因此需要多种统计方法来研究自然种群中的选择作用。
