Muñoz Matías I, Goutte Sandra, Ellers Jacintha, Halfwerk Wouter
Department of Ecological Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
New York University Abu Dhabi, Abu Dhabi, UAE.
J Evol Biol. 2020 Dec;33(12):1749-1757. doi: 10.1111/jeb.13713. Epub 2020 Oct 18.
Animals show a rich diversity of signals and displays. Among the many selective forces driving the evolution of communication signals, one widely recognized factor is the structure of the environment where animals communicate. In particular, animals communicating by sounds often emit acoustic signals from specific locations, such as high up in the air, from the ground or in the water. The properties of these different display sites may impose different constraints on sound production, and therefore drive signal evolution. Here, we used comparative phylogenetic analyses to assess the relationship between calling site (aquatic versus nonaquatic), body size and call dominant frequency of 160 frog species from the families Ranidae, Leptodactylidae and Hylidae. We found that the frequency of frogs calling from the water was lower than that of species calling outside of the water, a trend that was consistent across the three families studied. Furthermore, phylogenetic path analysis revealed that call site had both direct and indirect effects on call frequency. Indirect effects were mediated by call site influencing male body size, which in turn was negatively associated with call frequency. Our results suggest that properties of display sites can drive signal evolution, most likely not only through morphological constraints imposed on the sound production mechanism, but also through changes in body size, highlighting the relevance of the interplay between morphological adaptation and signal evolution. Changes in display site may therefore have important evolutionary consequences, as it may influence sexual selection processes and ultimately may even promote speciation.
动物表现出丰富多样的信号和展示行为。在驱动通讯信号进化的众多选择力量中，一个被广泛认可的因素是动物进行交流的环境结构。特别是，通过声音进行交流的动物通常会从特定位置发出声学信号，比如在空中高处、地面或水中。这些不同展示地点的特性可能会对声音产生施加不同的限制，从而推动信号进化。在此，我们运用比较系统发育分析来评估蛙科、细趾蟾科和雨蛙科160种蛙类的鸣叫地点（水生与非水生）、体型与鸣叫主频之间的关系。我们发现，在水中鸣叫的蛙类的频率低于在水外鸣叫的物种，这一趋势在所研究的三个科中都是一致的。此外，系统发育路径分析表明，鸣叫地点对鸣叫频率既有直接影响，也有间接影响。间接影响是通过鸣叫地点影响雄性体型来介导的，而雄性体型又与鸣叫频率呈负相关。我们的结果表明，展示地点的特性能够驱动信号进化，很可能不仅是通过对声音产生机制施加形态学限制，还通过体型的变化，这突出了形态适应与信号进化之间相互作用的相关性。展示地点的变化因此可能具有重要的进化后果，因为它可能影响性选择过程，最终甚至可能促进物种形成。
