the role of environmental and biological factors in determining Arctic species richness and community structure

生物世界最引人注目但又最不为人所知的特征之一是其巨大的多样性。解释生物多样性的起源和维持是生态学和进化中一个长期存在的难题。在每个主要的生态类别中，竞争可能会使除了一个或几个合适的物种之外的所有物种被淘汰，但事实显然并非如此。我的工作重点是描述和解释北极生态系统中物种丰富度和共存的模式。与南方系统相比，这些系统的生物多样性较低，因此是进行全群落分析的理想目标。此外，我和许多合作者在加拿大低北极地区（马尼托巴省丘吉尔）工作了几年，建立了一个“DNA条形码参考库”，可以使用DNA序列识别幼虫的生命阶段和小型神秘生物，这为拟议的研究提供了便利。这些生命阶段通常构成了最丰富和最多样化的生态系统元素，而识别问题以前限制了我们进行群落分析的能力。这项最近的工作使生物多样性和群落结构的分析在几年前是不可能的。拟议中的研究将检验北极群落是否仅仅由能够在这种环境中定居和生存的物种组成，或者是否有证据表明，群落结构是通过竞争和捕食等生物相互作用形成的。这项工作将在规模上是新颖的，包括广泛的无脊椎动物群体，陆地和淡水栖息地，当地和区域地理尺度，以及多种营养水平。这种覆盖范围将允许评估观察到的模式是系统特有的还是反映了社区聚集的更一般的生态原则。这项工作预计将有助于解决关于不同类型的确定性力量的相对作用的争论，包括栖息地选择性和生物相互作用，而不是影响群落多样性和结构的随机性。

One of the most striking, but least understood, features of the biological world is its enormous diversity. Explaining the origin and maintenance of biodiversity is a long-standing puzzle in ecology and evolution. Competition might be intuitively expected to eliminate all but one or a few fit species in each major ecological category, but this is clearly not the case. My work focuses on characterizing and explaining patterns of species richness and co-existence in Arctic ecosystems. These systems are ideal targets for community-wide analyses due to their lower biodiversity compared with southern systems. Moreover, the proposed research is facilitated by the fact that numerous collaborators and I have been working for several years at a low-Arctic Canadian site (Churchill, Manitoba) to build a "DNA barcode reference library", which permits the identification of larval life stages and small cryptic organisms using DNA sequences. Such life stages commonly constitute the most abundant and diverse ecosystem elements, and problems with identification previously limited our ability to conduct community analyses. This recent work has enabled biodiversity and community structure analysis on a scale that would have been impossible only a few years ago. The proposed research will test whether Arctic communities simply consist of species that were able to colonize and survive in this environment or whether there is evidence of community structuring via biological interactions such as competition and predation. This work will be novel in scale, encompassing a broad range of invertebrate groups, terrestrial and freshwater habitats, local and regional geographic scales, and multiple trophic levels. This coverage will permit assessments of whether observed patterns are system specific or reflect more general ecological principles of community assembly. This work is expected to contribute to resolving the debate over the relative roles of different types of deterministic forces, including habitat selectivity and biotic interactions, as opposed to stochasticity in influencing community diversity and structure.