Size, ornamentation, and flight feather morphology promote within-pair paternity in a sexually dimorphic passerine

Morphology in sexually dimorphic species is related to increased opportunity for sexual selection when traits reflect individual quality. In socially monogamous species, it may function to increase variance in reproductive success if exaggerated traits are related to the opportunity to engage in extra-pair paternity (EPP). Nonetheless, it is poorly understood if ornamental versus functional traits are differentially related to the distribution of paternity across individuals. We examined EPP in the Scissor-tailed Flycatcher (Tyrannus forficatus), a sexually dimorphic suboscine passerine, to determine how flight feather morphology (both ornamental and related to flight performance), ornamental coloration, and flight performance were related to paternity for males and females. We assessed paternity at 140 nests across 7 years and found that 73% of nests contained extra-pair young with 59% of nestlings resulted from extra-pair fertilizations. Males that secured paternity with their social ...

性二型物种的形态特征，当其可反映个体品质时，与性选择机会的提升存在显著关联。对于社会一夫一妻制物种而言，若夸张形态性状与个体参与婚外父权（extra-pair paternity, EPP）的机会相关，则此类性状或可提高繁殖成功率的变异幅度。尽管如此，学界目前仍未明确装饰性性状与功能性性状是否会对个体间的父权分布产生差异化影响。本研究以性二型亚鸣禽雀形目鸟类剪尾王霸鹟（Tyrannus forficatus）为研究对象，对其婚外父权现象开展调查，以明确飞羽形态（涵盖装饰性性状与飞行性能相关性状）、装饰性体色以及飞行性能与雌雄个体父权的关联模式。我们对7年间的140个巢穴进行了父权鉴定，结果显示73%的巢穴存在婚外子代，且59%的雏鸟由婚外受精产生。成功通过社会配偶获得父权的雄性……