Spencer K A, Buchanan K L, Goldsmith A R, Catchpole C K
School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Horm Behav. 2003 Aug;44(2):132-9. doi: 10.1016/s0018-506x(03)00124-7.
In a wide range of bird species, females have been shown to express active preferences for males that sing more complex songs. Current sexual selection theory predicts that for this signal to remain an honest indicator of male quality, it must be associated with an underlying cost of development or maintenance. There has been considerable debate questioning the costs associated with song production and learning. Recently, the nutritional stress hypothesis proposed that song complexity could act as an indicator of early developmental history, since the song control nuclei in the brain are laid down early in life. Here we test the nutritional stress hypothesis, by investigating the effects of dietary stress on the quality of adult song produced. In addition, we tested the effects of elevated corticosterone during development on song production to test its possible involvement in mediating the effects of developmental stress. The results demonstrate that both dietary restriction and elevated corticosterone levels significantly reduced nestling growth rates. In addition, we found that experimentally stressed birds developed songs with significantly shorter song motif duration and reduced complexity. These results provide novel experimental evidence that complex song repertoires may have evolved as honest signals of male quality, by indicating early developmental rearing conditions.
在众多鸟类物种中，已表明雌性对歌声更为复杂的雄性表现出主动偏好。当前的性选择理论预测，要使这种信号始终诚实地反映雄性质量，它必须与潜在的发育或维持成本相关联。关于与歌曲产生和学习相关的成本存在大量争议。最近，营养应激假说提出，歌曲复杂性可以作为早期发育历史的一个指标，因为大脑中的歌曲控制核在生命早期就已形成。在此，我们通过研究饮食应激对成年后产生的歌声质量的影响来检验营养应激假说。此外，我们测试了发育过程中皮质酮水平升高对歌曲产生的影响，以检验其可能参与介导发育应激的作用。结果表明，饮食限制和皮质酮水平升高均显著降低了雏鸟的生长速度。此外，我们发现，经实验产生应激反应的鸟类所发育出的歌曲，其歌曲主题时长显著缩短且复杂性降低。这些结果提供了新的实验证据，表明复杂的歌曲 repertoire 可能通过指示早期发育饲养条件而进化为雄性质量的诚实信号。
