Data from: Biogeography predicts macro-evolutionary patterning of gestural display complexity in a passerine family

Gestural displays are incorporated into the signaling repertoire of numerous animal species. These displays range from complex signals that involve impressive and challenging maneuvers, to simpler displays or no gesture at all. The factors that drive this evolution remain largely unclear, and we therefore investigate this issue in New World blackbirds by testing how factors related to a species’ geographical distribution and social mating system predict macro-evolutionary patterns of display elaboration. We report that species inhabiting temperate regions produce more complex displays than species living in tropical regions, and we attribute this to i) ecological factors that increase the competitiveness of the social environment in temperate regions, and ii) different evolutionary and geological contexts under which species in temperate and tropical regions evolved. Meanwhile, we find no evidence that social mating system predicts species differences in display complexity, which is consistent with the idea that gestural displays evolve independently of social mating system. Together, these results offer some of the first insight into the role played by geographic factors and evolutionary context in the evolution of the remarkable physical displays of birds and other vertebrates.

姿态展示（gestural display）已被纳入众多动物物种的信号行为库（signaling repertoire）。这类展示的谱系跨度极大，从包含精妙且高难度动作的复杂信号，到简易展示乃至完全不使用姿态的形式均有涵盖。目前驱动这类展示演化的核心因素在很大程度上仍未明确，因此我们以新大陆黑鹂（New World blackbirds）为研究类群，通过检验与物种地理分布、社会婚配制度（social mating system）相关的因素能否预测姿态展示复杂度的宏观进化模式（macro-evolutionary patterns），来探究这一科学问题。研究结果表明，栖息于温带地区的物种其姿态展示复杂度显著高于热带物种，我们将这一现象归因于两方面：其一，温带地区的生态因素强化了社会环境的竞争烈度；其二，温带与热带物种的进化及地质背景存在显著差异。与此同时，我们未发现社会婚配制度能够解释物种间展示复杂度差异的证据，这与姿态展示演化独立于社会婚配制度的学术观点一致。综上，本研究首次揭示了地理因素与进化背景在鸟类及其他脊椎动物（vertebrates）精妙肢体展示演化过程中的关键作用。