Data from: Is sociality required for the evolution of communicative complexity? Evidence weighed against alternative hypotheses in diverse taxonomic groups

Complex social communication is expected to evolve whenever animals engage in many and varied social interactions; that is, sociality should promote communicative complexity. Yet informal comparisons among phylogenetically independent taxonomic groups seem to cast doubt on the putative role of social factors in the evolution of complex communication. Here, we provide a formal test of the sociality hypothesis along side alternative explanations for the evolution of communicative complexity. We compiled data documenting variation in signal complexity among closely related species for several case study groups – ants, frogs, lizards and birds – and used new phylogenetic methods to investigate the factors underlying communication evolution. Social factors were only implicated in the evolution of complex visual signals in lizards. Ecology, and to some degree allometry, were most likely explanations for complexity in the vocal signals of frogs (ecology) and birds (ecology and allometry). There was some evidence for adaptive evolution in the pheromone complexity of ants, although no compelling selection pressure was identified. For most taxa, phylogenetic null models were consistently ranked above adaptive models and, for some taxa, signal complexity seems to have accumulated in species via incremental or random changes over long periods of evolutionary time. Becoming social presumably lead to the origin of social communication in animals, but its subsequent influence on the trajectory of signal evolution has been neither clear-cut nor general among taxonomic groups.

当动物开展大量且多样的社会互动时，复杂的社会交流通常会随之演化；换言之，社会性应当会推动交流复杂度的提升。然而，针对系统发育独立的分类群所开展的非正式比较研究，似乎对社会因素在复杂交流演化中的假定作用提出了质疑。本研究对社会性假说开展了正式检验，并同时探讨了交流复杂度演化的其他替代性解释。我们汇编了多个研究类群——蚂蚁、蛙类、蜥蜴与鸟类——的近缘物种间信号复杂度差异的相关数据，并采用全新的系统发育分析方法探究了驱动交流演化的核心因素。研究结果显示，仅在蜥蜴类群中，社会因素与复杂视觉信号的演化存在关联。蛙类发声信号的复杂度最可能由生态因素解释，而鸟类发声信号的复杂度则同时由生态因素与异速生长（在一定程度上）共同解释。蚂蚁信息素复杂度的演化存在一定的适应性演化证据，但尚未明确其关键的选择压力。对于多数类群而言，系统发育零模型的拟合优度始终高于适应性模型；部分类群的信号复杂度似乎是在漫长的演化历程中，通过渐进式或随机变化逐步积累形成的。社会性的起源固然推动了动物社会交流的产生，但其后续对信号演化轨迹的影响，在不同分类群之间既非明确单一，也不具有普遍性。