Nowicki Stephen, Searcy William A
Department of Biology, Duke University, Durham, North Carolina 27708, USA.
Ann N Y Acad Sci. 2004 Jun;1016:704-23. doi: 10.1196/annals.1298.012.
Analyzing the function of song and its evolution as a communication signal provides an essential backdrop for understanding the physiological and neural mechanisms responsible for song learning, perception, and production. The reverse also is true-understanding the mechanisms underlying song learning provides insight into how song has evolved as a communication signal. Song has two primary functions: to repel other males from a defended space and to attract females and stimulate their courtship. The developmental stress hypothesis we present here builds on studies of the development of the song system to suggest how learned features of song, including complexity and local dialect structure, can serve as indicators of male quality useful to females in mate choice. The link between song and male quality depends on the fact that brain structures underlying song learning largely develop during the first few months post-hatching and that during this same period, songbirds are likely to be subject to nutritional and other developmental stresses. Individuals faring well in the face of stress are able to invest more resources to brain development and are expected to be correspondingly better at song learning. Learned features of song thus become reliable indicators of male quality, with reliability maintained by the developmental costs of song. Data from both field and laboratory studies are now beginning to provide broad support for the developmental stress hypothesis, illustrating the utility of connecting mechanistic and evolutionary analyses of song learning.
分析鸣叫的功能及其作为一种通讯信号的进化过程，为理解负责鸣叫学习、感知和产生的生理及神经机制提供了重要背景。反之亦然——理解鸣叫学习背后的机制有助于深入了解鸣叫作为一种通讯信号是如何进化的。鸣叫有两个主要功能：将其他雄性驱赶出其保卫的领地，以及吸引雌性并激发它们的求偶行为。我们在此提出的发育应激假说，是基于对鸣叫系统发育的研究，旨在说明鸣叫的习得特征，包括复杂性和地方方言结构，如何能够作为雄性质量的指标，对雌性在配偶选择中有用。鸣叫与雄性质量之间的联系取决于这样一个事实，即鸣叫学习所依赖的脑结构在孵化后的头几个月里大量发育，而且在同一时期，鸣禽可能会受到营养和其他发育应激的影响。在面对应激时表现良好的个体能够将更多资源投入到大脑发育中，因此预计在鸣叫学习方面会相应地表现得更好。鸣叫的习得特征因此成为雄性质量的可靠指标，其可靠性由鸣叫的发育成本维持。来自野外和实验室研究的数据现在开始为发育应激假说提供广泛支持，说明了将鸣叫学习的机制分析和进化分析联系起来的实用性。
