Department of Zoology, University of Melbourne, Victoria, Australia.
J Evol Biol. 2010 Nov;23(11):2501-6. doi: 10.1111/j.1420-9101.2010.02109.x.
A commonly held principle in visual ecology is that communication compromises camouflage: while visual signals are often conspicuous, camouflage provides concealment. However, some traits may have evolved for communication and camouflage simultaneously, thereby overcoming this functional compromise. Visual patterns generally provide camouflage, but it was suggested that a particular type of visual pattern – avian barred plumage – could also be a signal of individual quality. Here, we test if the evolution of sexual dimorphism in barred plumage, as well as differences between juvenile and adult plumage, indicate camouflage and/or signalling functions across the class Aves. We found a higher frequency of female- rather than male-biased sexual dimorphism in barred plumage, indicating that camouflage is its most common function. But we also found that, compared to other pigmentation patterns, barred plumage is more frequently biased towards males and its expression more frequently restricted to adulthood, suggesting that barred plumage often evolves or is maintained as a sexual communication signal. This illustrates how visual traits can accommodate the apparently incompatible functions of camouflage and communication, which has implications for our understanding of avian visual ecology and sexual ornamentation.
视觉生态学中的一个普遍原则是，通讯会损害伪装：虽然视觉信号通常很显眼，但伪装提供了隐蔽性。然而，有些特征可能同时为通讯和伪装而进化，从而克服了这种功能上的权衡。视觉模式通常提供伪装，但有人认为，一种特殊类型的视觉模式——鸟类的横斑羽——也可以作为个体质量的信号。在这里，我们测试了在鸟类中，横斑羽的性二型性的进化，以及幼鸟和成年羽之间的差异，是否表明了伪装和/或信号功能。我们发现，横斑羽中雌性而非雄性的性二型性更为常见，这表明伪装是其最常见的功能。但我们也发现，与其他色素模式相比，横斑羽更多地偏向于雄性，而且更多地局限于成年期表达，这表明横斑羽通常是作为一种性通讯信号而进化或维持的。这说明了视觉特征如何适应伪装和通讯这两种看似不兼容的功能，这对我们理解鸟类的视觉生态学和性装饰有重要意义。
