The role of ecological filtering, dispersal limitation and species traits in determining food web structure and function

为什么不是所有的物种都存在？物种数量有限的事实又如何影响食物网的功能呢？我提议对加拿大、哥斯达黎加和巴西的无脊椎动物食物网进行研究，将回答这两个问题。物种可能不会到处出现，因为它们没有足够的时间或机会殖民（扩散限制），因为栖息地不合适（栖息地过滤），因为其他物种限制它们的发生（生物过滤），或者因为一系列偶然事件导致物种在当地灭绝（生态漂移）。我将通过观察和移植来区分这些选择。我预测这些机制的相对重要性在小型和大型生物之间，以及在捕食者和猎物之间会有所不同。在这些类型特征上不同的物种也可能在食物网中扮演非常不同的功能角色，我们预测，因此，对扩散限制或栖息地过滤的操纵也将影响能量和营养物质在食物网中的流动速度。最后，物种之间的功能性状差异可能具有强烈的进化信号，例如近亲物种具有相似的性状。如果是这样，群落中物种的净亲缘关系（“系统发育多样性”）可能与生态系统功能密切相关。

Why don't all species occur everywhere? And how does the fact that species are limited in their occurrence affect how food webs function? My proposed research with invertebrate food webs in Canada, Costa Rica and Brazil will answer both of these questions. Species may not occur everywhere because they have not had enough time or opportunity to colonize (dispersal limitation), because the habitat is not suitable (habitat filtering), because other species restrict them from occurring (biotic filtering) or because a series of chance events has led to the species going locally extinct (ecological drift). I will distinguish between these options using observations and transplants. I predict that the relative importance of these mechanisms will differ between small and large organisms, and between predators and their prey. Species that differ in these types of traits are also likely to play a very different functional role in food webs, and we predict that manipulations of dispersal limitation or habitat filtering will therefore also the rate at which energy and nutrients flow through the food web. Finally, functional trait differences between species may have a strong evolutionary signal, such that closely related species have similar traits. If so, the net relatedness of species in a community ("phylogenetic diversity") may be a strong correlate of ecosystem function.