The evolution of sexually dimorphic ornamentation should reflect sex differences in a form of parental care, incubation behavior, but empirical support is scarce after controlling for phylogenetic inertia. Here, using phylogenetic comparative methods in swallows and martins (Aves: Hirundinidae), we studied the evolution of sexual dimorphism in tail length in relation to two incubation types, female-only and biparental incubation. We found that species with biparental incubation were more likely to have sexually monomorphic tails compared to species with female-only incubation. Furthermore, an analysis of evolutionary pathways suggested interdependent evolution of biparental incubation and sexual tail dimorphism; transitions to biparental incubation and sexual tail dimorphism were less likely to occur than transitions from that state. This finding is consistent with the hypothesis that selection on male ornamentation matters during the incubation period. We also confirmed that species with biparental incubation had significantly lower rates of extra-pair paternity compared to species with female-only incubation in this clade, providing additional support for the importance of selection on male ornamentation during the incubation period. The current study is one of few phylogenetic comparative studies demonstrating the correlated evolution of biparental incubation and sexual dimorphism in ornamentation.

中文翻译：

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燕子和马丁的双亲孵化和有性尾巴单态性的相关进化（Aves：Hirundinidae）

性别二态纹饰的进化应该以亲代照料、孵化行为的形式反映性别差异，但在控制系统发育惰性后缺乏经验支持。在这里，我们使用燕子和马丁斯（Aves：Hirundinidae）的系统发育比较方法，研究了与两种孵化类型（雌性和双亲孵化）相关的尾长性别二态性的进化。我们发现，与只有雌性孵化的物种相比，双亲孵化的物种更有可能具有性单态的尾巴。此外，对进化途径的分析表明双亲孵化和有性尾巴二态性的相互依赖的进化；与从该状态的转变相比，向双亲孵化和性尾二态性的转变不太可能发生。这一发现与潜伏期对雄性纹饰的选择很重要的假设一致。我们还证实，在这个进化枝中，双亲孵化的物种与仅雌性孵化的物种相比，双亲孵化的物种具有显着较低的额外亲子关系，这为在孵化期间选择雄性纹饰的重要性提供了额外的支持。目前的研究是少数系统发育比较研究之一，证明了装饰中双亲孵化和性别二态性的相关进化。我们还证实，在这个进化枝中，双亲孵化的物种与仅雌性孵化的物种相比，双亲孵化的物种具有显着较低的额外亲子关系，这为在孵化期间选择雄性纹饰的重要性提供了额外的支持。目前的研究是少数系统发育比较研究之一，证明了装饰中双亲孵化和性别二态性的相关进化。我们还证实，在这个进化枝中，双亲孵化的物种与仅雌性孵化的物种相比，双亲孵化的物种具有显着较低的额外亲子关系，这为在孵化期间选择雄性纹饰的重要性提供了额外的支持。目前的研究是少数系统发育比较研究之一，证明了装饰中双亲孵化和性别二态性的相关进化。