Martin Thomas E, Badyaev Alexander V
US National Biological Service, Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, Montana, 59812.
Department of Biological Sciences, University of Montana, Missoula, Montana, 59812.
Evolution. 1996 Dec;50(6):2454-2460. doi: 10.1111/j.1558-5646.1996.tb03631.x.
Examinations of variation in plumage dichromatism in birds have focused on male plumage brightness and largely neglected variation in female plumage brightness. Nest predation previously was concluded to constrain male brightness and thereby reduce dimorphism in ground-nesting birds based on an incorrect assumption that nest predation is greater for ground nests. Correlations of plumage brightness and dichromatism with nest predation have never been tested directly and we do so here with data for warblers (Parulinae) and finches (Carduelinae). We show that male plumage brightness varies among nest heights, but in a pattern that is not correlated with nest predation. Female plumage brightness also varies among nest heights, but in a pattern that differs from males, and one in which variation in female plumage brightness was negatively correlated with nest predation. These results suggest that nest predation may place greater constraints on female than male plumage brightness, at least in taxa where only females incubate eggs and brood young. These results also show that female plumage patterns vary at least partly independently of male patterns and emphasize the need to include consideration of both female and male plumage variation in tests of plumage dimorphism. Plumage dimorphism differs between ground and off-ground nesters as previously described and, if anything, the relationship between plumage dimorphism and nest predation was positive rather than negative as previously argued.
对鸟类羽毛两性异形变化的研究主要集中在雄性羽毛的亮度上，而很大程度上忽略了雌性羽毛亮度的变化。此前基于地面巢穴遭受的巢捕食率更高这一错误假设，得出巢捕食会限制雄性羽毛亮度从而减少地面筑巢鸟类两性异形的结论。羽毛亮度和两性异形与巢捕食之间的相关性从未得到直接检验，我们在此利用莺科（Parulinae）和雀科（Carduelinae）的数据进行检验。我们发现，雄性羽毛亮度在不同巢高之间存在差异，但这种模式与巢捕食并无关联。雌性羽毛亮度在不同巢高之间也存在差异，但其模式与雄性不同，且雌性羽毛亮度的变化与巢捕食呈负相关。这些结果表明，至少在仅由雌性孵卵和育雏的类群中，巢捕食对雌性羽毛亮度的限制可能比对雄性更大。这些结果还表明，雌性羽毛模式至少部分独立于雄性模式变化，并强调在检验羽毛两性异形时需要同时考虑雌性和雄性羽毛的变化。如先前所述，地面筑巢鸟类和非地面筑巢鸟类的羽毛两性异形存在差异，而且，如果有什么不同的话，羽毛两性异形与巢捕食之间的关系是正相关而非如先前所说的负相关。
