Social call divergence in bats: a comparative analysis

Acoustic signals mediate important life history events in a variety of species, providing new vistas for understanding speciation. It has been proposed that animal acoustic signals undergo complex interactions among morphology, ecology, social pressure, and phylogenetic history. Yet, the relative importance of these factors in shaping acoustic divergence is rarely assessed within a comparative framework. Herein, we aim to investigate the key determinants of social call divergence across 31 bat species from 5 families. We compiled a wide data set on bat aggressive calls, body size, foraging habitats, foraging modes, climatic conditions, colony size, and phylogenetic components. We identified remarkable interspecific divergence versus within-species variation in aggressive vocalizations. Despite weak effects of ecological factors, colony size, body size, and phylogenetic components accounted for the majority of variation in call parameters among species. The colony size and body size played a major role in influencing spectral parameters, whereas phylogenetic relationships determined call duration and minimum frequency. Together, our findings constitute convincing evidence that sociality, morphological constraint, and phylogenetic constraint mold social call divergence in bats. This study expands our limited knowledge of the evolution of bat social calls, and highlights the importance of sociality in driving acoustic phenotype diversity.

声学信号（acoustic signals）在众多物种的关键生命史事件中发挥介导作用，为理解物种形成（speciation）提供了全新视角。已有研究提出，动物声学信号会在形态学（morphology）、生态学（ecology）、社会压力以及系统发育历史（phylogenetic history）之间发生复杂的相互作用。然而，在比较框架（comparative framework）下，鲜有研究评估这些因素在塑造声学分化（acoustic divergence）中的相对重要性。本研究旨在探究来自5个科的31个蝙蝠物种的社交鸣叫（social call）分化的关键决定因素。我们收集了涵盖蝙蝠攻击鸣叫（aggressive calls）、体型大小、觅食生境（foraging habitats）、觅食方式（foraging modes）、气候条件、集群大小（colony size）以及系统发育组分（phylogenetic components）的多维度数据集。我们发现，蝙蝠攻击鸣叫存在显著的种间分化与种内变异。尽管生态因素的影响相对微弱，但集群大小、体型大小与系统发育组分解释了物种间鸣叫参数（call parameters）变异的主体部分。集群大小与体型大小对频谱参数（spectral parameters）具有显著调控作用，而系统发育关系（phylogenetic relationships）则决定了鸣叫时长（call duration）与最低频率（minimum frequency）。综上，我们的研究结果提供了有力证据，证明社会性（sociality）、形态约束（morphological constraint）与系统发育约束（phylogenetic constraint）共同塑造了蝙蝠的社交鸣叫分化。本研究拓展了我们对蝙蝠社交鸣叫演化的有限认知，并强调了社会性在推动声学表型（acoustic phenotype）多样性中的重要作用。