Smith Thomas Bates
Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, CA, 94720, USA.
Evolution. 1990 Jul;44(4):832-842. doi: 10.1111/j.1558-5646.1990.tb03808.x.
Evidence for natural selection on seven bill and body characters is examined in the two bill morphs of the African estrildid finch Pyrenestes ostrinus. Two regression methods are used in examining natural selection in association with survivorship: a parametric (Lande and Arnold, 1983) and a non-parametric (Schluter, 1988) method. Selection was estimated in adult males, females and juveniles over a four-year period in a population in south-central Cameroon. Selection was common among groups but patterns differed and depended on the method used in detecting selection. The non-parametric method revealed evidence for disruptive selection occurring on bill width and is explained within the context of known feeding efficiencies and the hardness of important seeds in finch diets. Directional selection was common on bill characters in all groups, but infrequent on other characters. There was no evidence of selection on generalized size or shape characters. Selection on bill characters was common across groups despite low annual variation in rainfall. This contrasts with studies of Galápagos finches in which selection is frequently associated with dramatic changes in food supply caused by high variance in annual rainfall. Patterns of selection on bill traits in P. ostrinus also differ from those in song sparrows and Galápagos finches by exhibiting evidence for natural selection on all bill dimensions.
在非洲梅花雀Pyrenestes ostrinus的两种喙形态中，研究了自然选择对七种喙部和身体特征的影响。在研究与生存相关的自然选择时，使用了两种回归方法：一种是参数方法（兰德和阿诺德，1983年），另一种是非参数方法（施卢特，1988年）。在喀麦隆中南部的一个种群中，对成年雄性、雌性和幼鸟在四年时间里的选择情况进行了估计。选择在不同群体中很常见，但模式不同，并且取决于用于检测选择的方法。非参数方法揭示了在喙宽度上发生分裂选择的证据，并在已知的取食效率和雀类饮食中重要种子硬度的背景下进行了解释。定向选择在所有群体的喙特征上很常见，但在其他特征上不常见。没有证据表明对总体大小或形状特征存在选择。尽管年降雨量变化较小，但对喙特征的选择在不同群体中很常见。这与加拉帕戈斯雀的研究形成对比，在加拉帕戈斯雀的研究中，选择经常与年降雨量的高变化导致的食物供应的剧烈变化相关。Pyrenestes ostrinus喙部特征的选择模式也与歌雀和加拉帕戈斯雀不同，因为在所有喙部维度上都显示出自然选择的证据。
