Department of Evolutionary Ecology, National Museum of Natural Sciences, CSIC, Jose Gutierrez Abascal 2, 28006, Madrid, Spain.
School of Biology, The Faculty of Biological Sciences, University of Leeds, LS2 9JT, Leeds, UK.
Evolution. 2020 Mar;74(3):559-572. doi: 10.1111/evo.13925. Epub 2020 Jan 30.
Adaptive explanations for the evolution of extra-pair paternity (EPP) suggest that females seek extra-pair copulations with high quality males. Still, the link between ornamentation, individual quality, and paternity remains unclear. Moreover, honest signaling is essential when explaining EPP because it is needed for sexual selection to occur; yet, it is understudied in multiple ornaments. Because blue tits (Cyanistes caeruleus) show variable color expression in several plumage patches, we tested: (i) over two seasons, whether males in better condition, more ornamented and less infected by blood parasites gain EPP and have higher reproductive success, and (ii) over three seasons, whether mating patterns affect color change. Males with more saturated yellow feathers, brighter tails, and in better condition had higher reproductive success in one of the seasons. Contrary to expectation, in another season, males that gained EPP were parasitized by blood parasites, suggesting increased vector exposure during extra-pair copulations. Our results for two seasons show that males siring more extra-pair young were older and grew brighter cheek or tail feathers for the following season. Despite the increased mating costs, in socially monogamous avian systems, high quality males incur in EPP without compromising traits that may be under sexual selection.
针对配偶外交配（EPP）进化的适应性解释表明，雌性会与高质量的雄性进行配偶外交配。然而，装饰、个体质量和父权之间的联系仍不清楚。此外，在解释 EPP 时，诚实的信号传递至关重要，因为这是发生性选择所必需的；然而，在多种装饰物中，它的研究还很不足。由于蓝山雀（Cyanistes caeruleus）在几个羽毛斑块中表现出可变的颜色表达，我们测试了：（i）在两个季节中，身体状况更好、装饰更多、受血液寄生虫感染更少的雄性是否会获得配偶外交配并拥有更高的繁殖成功率，以及（ii）在三个季节中，交配模式是否会影响颜色变化。在一个季节中，具有更饱和的黄色羽毛、更鲜艳的尾巴和更好身体状况的雄性繁殖成功率更高。与预期相反，在另一个季节中，获得配偶外交配的雄性被血液寄生虫寄生，这表明在配偶外交配期间接触到的媒介增加。我们在两个季节的结果表明，为更多配偶外幼崽提供亲代的雄性年龄更大，并且在下一个季节中脸颊或尾巴的羽毛颜色更鲜艳。尽管交配成本增加，但在社会一夫一妻制的鸟类系统中，高质量的雄性会获得配偶外交配，而不会损害可能受到性选择的特征。
