Department of Zoology, Edward Grey Institute of Field Ornithology, University of Oxford, Oxford, UK.
J Evol Biol. 2011 Jul;24(7):1584-97. doi: 10.1111/j.1420-9101.2011.02289.x. Epub 2011 May 17.
Avian plumage colours are some of the most conspicuous sexual ornaments, and yet standardized selection gradients for plumage colour have rarely been quantified. We examined patterns of fecundity selection on plumage colour in blue tits (Cyanistes caeruleus L.). When not accounting for environmental heterogeneity, we detected relatively few cases of selection. We found significant disruptive selection on adult male crown colour and yearling female chest colour and marginally nonsignificant positive linear selection on adult female crown colour. We discovered no new significant selection gradients with canonical rotation of the matrix of nonlinear selection. Next, using a long-term data set, we identified territory-level environmental variables that predicted fecundity to determine whether these variables influenced patterns of plumage selection. The first of these variables, the density of oaks within 50 m of the nest, influenced selection gradients only for yearling males. The second variable, an inverse function of nesting density, interacted with a subset of plumage selection gradients for yearling males and adult females, although the strength and direction of selection did not vary predictably with population density across these analyses. Overall, fecundity selection on plumage colour in blue tits appeared rare and inconsistent among sexes and age classes.
鸟类的羽毛颜色是最显眼的性装饰品之一，但羽毛颜色的标准化选择梯度很少被量化。我们研究了在蓝山雀（Cyanistes caeruleus L.）中对羽毛颜色的繁殖力选择模式。当不考虑环境异质性时，我们只检测到相对较少的选择案例。我们发现成年雄性冠色和幼雌胸色和胸缘有显著的破坏性选择，而成年雌性冠色有略微非显著的正线性选择。我们没有发现新的显著选择梯度，通过对非线性选择矩阵的典型旋转。接下来，使用一个长期数据集，我们确定了预测繁殖力的领地水平环境变量，以确定这些变量是否影响羽毛选择模式。第一个变量，巢周围 50 米内的橡树密度，仅影响幼雄的选择梯度。第二个变量，巢密度的倒数，与一组幼雄和成年雌鸟的羽毛选择梯度相互作用，尽管在这些分析中，选择的强度和方向并没有随种群密度的变化而可预测地变化。总体而言，在蓝山雀中，羽毛颜色的繁殖力选择似乎很少见，并且在性别和年龄组之间不一致。
