Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany.
Biol Lett. 2018 Apr;14(4). doi: 10.1098/rsbl.2018.0007.
Balancing selection is a major mechanism to maintain colour polymorphisms over evolutionary time. In common buzzards, variation in plumage colour was reportedly maintained by a heterozygote advantage: heterozygote intermediates had higher fitness than homozygote light and dark morphs. Here, we challenge one of the basic premises of the heterozygote advantage hypothesis, by testing whether plumage colour variation in common buzzards follows a one-locus two-allele inheritance model. Using a long-term population study with 202 families, we show that colour variation in buzzards is highly heritable. However, we find no support for a simple Mendelian one-locus two-allele model of inheritance. Our results rather suggest that buzzard plumage colour should be considered a quantitative polygenic trait. As a consequence, it is unlikely that the proposed heterozygote advantage is the mechanism that maintains this genetic variation. We hypothesize that plumage colour effects on fitness might depend on the environment, but this remains to be tested.
平衡选择是在进化过程中维持颜色多态性的主要机制。据报道，在普通秃鹫中，羽毛颜色的变异是由杂合优势维持的：杂合中间型比纯合浅色和深色形态具有更高的适应性。在这里，我们通过测试普通秃鹫的羽毛颜色变异是否遵循单基因座双等位基因遗传模型，来挑战杂合优势假说的一个基本前提。利用一项为期 20 年的包含 202 个家庭的长期群体研究，我们表明秃鹫的颜色变异具有高度的遗传性。然而，我们没有发现对简单的孟德尔单基因座双等位基因遗传模型的支持。我们的结果表明，秃鹫的羽毛颜色应该被视为一种数量多基因性状。因此，维持这种遗传变异的杂合优势机制不太可能。我们假设羽毛颜色对适应性的影响可能取决于环境，但这仍有待测试。
