Saturation of Bird Communities in the West Indies
Saturation of Bird Communities in the West Indies
复制标题
西印度群岛鸟类群落的饱和
作者：
J. Terborgh;J. Faaborg
该文件旨在解释图1所示的一组数据，该数据显示，西印度群岛两个广泛栖息地的鸟类物种数量达到了一个上限（饱和），该上限涵盖了广泛的岛屿物种数量。四个假设进行评估，以努力理解的结果：（1）岛屿社区，因为他们可以在不违反限制的相似性紧密包装;（2）岛屿鸟类的栖息地专家;（3）岛屿物种显示的容忍度的上限种间竞争;（4）岛屿物种的反应，减少竞争扩大栖息地谱和其他形式的生态释放。西印度群岛行会被发现是不那么紧密包装比大陆同行，消除假设1意义上的绝对限制包装，但不排除的可能性，岛屿物种竞争力较低的包装水平比大陆物种排除在外。每个岛屿的物种数量与现有生境数量密切相关（r2 = 0.90），大岛屿确实有一些生境范围有限的物种。然而，当测试的机会，扩大到非典型的栖息地，其中包含数量减少的竞争对手大多数物种这样做，这表明在丰富的动物群的栖息地范围主要划定扩散种间竞争。大量证据表明，岛屿物种无法入侵较富裕的大陆社区，在某些情况下，甚至是最富裕的大岛屿。我们推测，以牺牲竞争力为代价的生态多功能性的演变导致整个群岛的动物群的共适应扩散种间竞争的最大岛屿的特点的水平。各种形式的生态释放（丰富的扩展，栖息地光谱，垂直觅食范围），然后可以服务于较小的岛屿，以保持观察到的恒定的栖息地内物种数量在广泛的岛屿物种数量。
The paper is directed to interpreting the set of data displayed in figure 1, which shows that the number of bird species in two widespread West Indian habitats reaches a ceiling (saturation) that holds over a wide range of island species numbers. Four hypotheses are evaluated in an effort to understand the result: (1) Island communities are as tightly packed as they can be without breaching the limits of similarity; (2) island bird species are habitat specialists; (3) island species display an upper limit of tolerance of interspecific competition; (4) island species respond to reduced competition by broadening habitat spectra and other forms of ecological release. West Indian guilds are found to be less tightly packed than their mainland counterparts, eliminating hypothesis 1 in the sense of absolute limits to packing, but not foreclosing the possibility that island species are competitively excluded at lower packing levels than mainland species. The number of species per island increases in tight correlation (r2 = .90) with the number of available habitats, and large islands do contain numbers of species with restricted habitat ranges. Nevertheless, when tested with the opportunity to expand into atypical habitats containing reduced numbers of competitors most species do so, suggesting that habitat ranges in rich faunas are largely delineated by diffuse interspecific competition. A good deal of evidence suggests that island species are unable to invade richer mainland communities or, in some cases, even the richest large islands. We speculate that the evolution of ecological versatility at the expense of competitiveness leads to coadaptation of the fauna throughout the archipelago for the level of diffuse interspecific competition characteristic of the largest islands. Various forms of ecological release (expansion of abundance, habitat spectra, vertical foraging ranges) could then serve on smaller islands to maintain the observed constancy of within-habitat species numbers over a wide range of island species numbers.