Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
Evolution. 2012 Sep;66(9):2773-83. doi: 10.1111/j.1558-5646.2012.01635.x. Epub 2012 Apr 9.
Just as features of the physical and biotic environment constrain evolution of ecological and morphological traits, they may also affect evolution of communication systems. Here we analyze constraints on rates of vocal evolution, using a large dataset of New World avian sister taxa. We show that species breeding in tropical forests sing at generally lower frequencies and across narrower bandwidths than species breeding in open habitats, or at high latitudes. We attribute these restrictions on birdsong frequency to the presence of high-frequency insect noise and greater degradation of high-frequency sounds in tropical forests. We fit Ornstein-Uhlenbeck models to show that recent evolution of song frequency has been more greatly constrained in tropical forests than elsewhere, that is, songs have shown less tendency to diverge over time in tropical forests, consistent with inferred acoustic restrictions. In addition, we find that song frequency has evolved more rapidly overall at high latitudes in both forest and open habitats. Besides a larger available sound window, other factors contributing to more rapid divergence at high latitudes may include an overall increased intensity of sexual selection, occupation of more divergent habitats, and the presence of fewer competing species.
正如物理和生物环境的特征限制了生态和形态特征的进化一样，它们也可能影响通讯系统的进化。在这里，我们利用大量新的世界鸟类姐妹分类群的数据集来分析对发声进化速度的限制。我们表明，在热带森林中繁殖的物种的歌声通常比在开阔栖息地或高纬度地区繁殖的物种的歌声频率更低，带宽更窄。我们将鸟类歌声频率的这些限制归因于高频昆虫噪音的存在以及热带森林中高频声音的更大衰减。我们拟合了奥尔恩斯坦-乌伦贝克模型，以表明与其他地方相比，热带森林中歌曲频率的近期进化受到了更大的限制，也就是说，在热带森林中，歌声随时间的变化趋势较小，这与推断出的声学限制一致。此外，我们发现，无论是在森林还是开阔栖息地，高纬度地区的歌声频率总体上进化得更快。除了更大的可用声音窗口外，高纬度地区歌声进化更快的其他因素可能包括性选择强度的整体增加、更具差异性的栖息地的占据以及更少的竞争物种的存在。
