Tobias Martha L, Evans Ben J, Kelley Darcy B
Department of Biological Sciences, Columbia University, New York, NY, USA.
Department of Ecology, Evolutionary and Environmental Biology, Columbia University, New York, NY, USA ; Department of Biology, McMaster University, Hamilton, ON, Canada.
Behaviour. 2011;148(4):519-549. doi: 10.1163/000579511X569435.
For most frogs, advertisement calls are essential for reproductive success, conveying information on species identity, male quality, sexual state and location. While the evolutionary divergence of call characters has been examined in a number of species, the relative impacts of genetic drift or natural and sexual selection remain unclear. Insights into the evolutionary trajectory of vocal signals can be gained by examining how advertisement calls vary in a phylogenetic context. Evolution by genetic drift would be supported if more closely related species express more similar songs. Conversely, a poor correlation between evolutionary history and song expression would suggest evolution shaped by natural or sexual selection. Here, we measure seven song characters in 20 described and two undescribed species of African clawed frogs (genera and ) and four populations of . We identify three call types - click, burst and trill - that can be distinguished by click number, call rate and intensity modulation. A fourth type is biphasic, consisting of two of the above. Call types vary in complexity from the simplest, a click, to the most complex, a biphasic call. Maximum parsimony analysis of variation in call type suggests that the ancestral type was of intermediate complexity. Each call type evolved independently more than once and call type is typically not shared by closely related species. These results indicate that call type is homoplasious and has low phylogenetic signal. We conclude that the evolution of call type is not due to genetic drift, but is under selective pressure.
对于大多数青蛙来说，求偶鸣叫对于繁殖成功至关重要，它能传达有关物种身份、雄性品质、性状态和位置的信息。虽然已经在许多物种中研究了鸣叫特征的进化分歧，但遗传漂变或自然选择与性选择的相对影响仍不清楚。通过研究求偶鸣叫在系统发育背景下如何变化，可以深入了解声音信号的进化轨迹。如果亲缘关系更近的物种表现出更相似的鸣叫，那么就支持遗传漂变导致的进化。相反，进化历史与鸣叫表现之间的弱相关性则表明进化是由自然选择或性选择塑造的。在这里，我们测量了20种已描述和2种未描述的非洲爪蟾（属和）以及4个种群的7种鸣叫特征。我们识别出三种鸣叫类型——咔哒声、脉冲声和颤音——可以通过咔哒声数量、鸣叫速率和强度调制来区分。第四种类型是双相的，由上述两种组成。鸣叫类型的复杂性各不相同，从最简单的咔哒声到最复杂的双相鸣叫。对鸣叫类型变异的最大简约分析表明，祖先类型的复杂性处于中间水平。每种鸣叫类型都不止一次独立进化，并且密切相关的物种通常不共享鸣叫类型。这些结果表明鸣叫类型是同形的，并且系统发育信号较低。我们得出结论，鸣叫类型的进化不是由于遗传漂变，而是受到选择压力的影响。
