The evolution of sexually dimorphic tail feathers is not associated with tail skeleton dimorphism

Sexual selection can influence the evolution of sexually dimorphic exaggerated display structures. Herein, we explore whether such costly ornamental integumentary structures evolve independently or if they are correlated with phenotypic change in the associated skeletal system. In birds, elongate tail feathers have frequently evolved in males and are beneficial as intraspecific display structures but impart a locomotor/energetic cost. Using the sexually dimorphic tail feathers of several passeriform species as a model system, we test the hypothesis that taxa with sexually dimorphic tail feathers also exhibit sexual dimorphism in the caudal skeleton that supports the muscles and integument of the tail apparatus. Caudal skeletal morphology is quantified using both geometric morphometrics and linear morphometrics across four sexually dimorphic passeriform species and four closely related monomorphic species. Sexual dimorphism is assessed using permutational MANOVA. Sexual dimorphism in cau...性选择可影响具性二态性（sexual dimorphism）的夸张展示结构的演化。本研究旨在探讨这类具演化代价的装饰性被覆结构，究竟是独立演化，还是与相关骨骼系统的表型变化存在关联。在鸟类中，雄性个体常演化出延长的尾羽，这类结构作为种内展示结构具有演化优势，但同时会带来运动与能量代谢层面的代价。本研究以多种雀形目（Passeriformes）鸟类的具性二态性尾羽作为模型系统，验证如下假说：拥有具性二态性尾羽的类群，其支撑尾器肌肉与被覆组织的尾骨骼也会表现出性二态性。研究选取4种具性二态性尾羽的雀形目鸟类，以及4种亲缘关系相近的单态性鸟类，通过几何形态测量法（geometric morphometrics）与线性形态测量法（linear morphometrics）对其尾骨骼形态进行量化分析。采用置换多变量方差分析（permutational MANOVA）评估性二态性的存在与否。尾骨骼的性二态性在……