Department of Biology, University of Massachusetts, Amherst, MA 01003, USA.
Philos Trans R Soc Lond B Biol Sci. 2010 Apr 12;365(1543):1031-9. doi: 10.1098/rstb.2009.0289.
Populations with multiple morphological or behavioural types provide unique opportunities for studying the causes and consequences of evolutionary diversification. A population of the medium ground finch (Geospiza fortis) at El Garrapatero on Santa Cruz Island, Galápagos, features two beak size morphs. These morphs produce acoustically distinctive songs, are subject to disruptive selection and mate assortatively by morph. The main goal of the present study was to assess whether finches from this population are able to use song as a cue for morph discrimination. A secondary goal of this study was to evaluate whether birds from this population discriminate songs of their own locality versus another St Cruz locality, Borrero Bay, approximately 24 km to the NW. I presented territorial males with playback of songs of their own morph, of the other morph, and of males from Borrero Bay. Males responded more strongly to same-morph than to other-morph playbacks, showing significantly shorter latencies to flight, higher flight rates and closer approaches to the playback speaker. By contrast, I found only minor effects of locality on responsiveness. Evidence for morph discrimination via acoustic cues supports the hypothesis that song can serve as a behavioural mechanism for assortative mating and sympatric evolutionary divergence.
具有多种形态或行为类型的种群为研究进化多样化的原因和后果提供了独特的机会。在加拉帕戈斯群岛圣克鲁斯岛上的埃尔加拉帕泰罗，有一个中型地面雀（Geospiza fortis）种群，具有两种鸟喙大小形态。这些形态产生具有独特声学特征的歌声，受到破坏性选择的影响，并通过形态进行配偶选择。本研究的主要目的是评估来自该种群的雀是否能够使用歌声作为形态识别的线索。本研究的次要目的是评估来自该种群的鸟类是否能够区分自己所在地（西北约 24 公里的博雷罗湾）与另一个圣克鲁斯地区的歌声。我向领地雄性播放了自己形态、其他形态和博雷罗湾雄性的歌声。雄性对同形态的反应比对其他形态的反应更强烈，表现出飞行潜伏期明显缩短、飞行率更高和更接近播放扬声器。相比之下，我只发现了地点对反应性的微小影响。通过声学线索进行形态识别的证据支持了这样一种假设，即歌声可以作为一种行为机制，用于配偶选择和同域进化分歧。
