US Geological Survey Montana Cooperative Wildlife Research Unit, University of Montana, Montana 59812, USA.
Evolution. 2011 Jun;65(6):1607-22. doi: 10.1111/j.1558-5646.2011.01227.x. Epub 2011 Feb 3.
Causes of interspecific variation in growth rates within and among geographic regions remain poorly understood. Passerine birds represent an intriguing case because differing theories yield the possibility of an antagonistic interaction between nest predation risk and food delivery rates on evolution of growth rates. We test this possibility among 64 Passerine species studied on three continents, including tropical and north and south temperate latitudes. Growth rates increased strongly with nestling predation rates within, but not between, sites. The importance of nest predation was further emphasized by revealing hidden allometric scaling effects. Nestling predation risk also was associated with reduced total feeding rates and per-nestling feeding rates within each site. Consequently, faster growth rates were associated with decreased per-nestling food delivery rates across species, both within and among regions. These relationships suggest that Passerines can evolve growth strategies in response to predation risk whereby food resources are not the primary limit on growth rate differences among species. In contrast, reaction norms of growth rate relative to brood size suggest that food may limit growth rates within species in temperate, but not tropical, regions. Results here provide new insight into evolution of growth strategies relative to predation risk and food within and among species.
种内和种间生长率变化的原因在地理区域内仍知之甚少。雀形目鸟类是一个有趣的案例，因为不同的理论产生了筑巢捕食风险和食物传递率对生长率进化之间的拮抗相互作用的可能性。我们在三大洲的 64 种雀形目物种中测试了这一可能性，包括热带、北温带和南温带。在种内而不是种间，生长率随雏鸟捕食率的增加而强烈增加。通过揭示隐藏的异速缩放效应，进一步强调了筑巢捕食的重要性。在每个地点内，雏鸟捕食风险还与总喂养率和每窝雏鸟喂养率降低有关。因此，在种内和种间，较快的生长率与每窝雏鸟食物传递率降低有关。这些关系表明，雀形目鸟类可以进化出应对捕食风险的生长策略，从而使食物资源不是物种间生长率差异的主要限制因素。相比之下，相对窝大小的生长率反应规范表明，在温带地区而不是热带地区，食物可能限制了物种内的生长率。本研究结果为深入了解物种内和种间的捕食风险和食物对生长策略的进化提供了新的视角。
