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鲜为人知的特征之一就是其巨大的多样性。解释生物多样性的起源和维持是生态学和进化论中一个长期存在的难题。从直觉上看，竞争可能会导致每个主要生态类别中只有一个或几个合适的物种消失，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，因此是全社区分析的理想目标。此外，由于我和许多合作者多年来一直在加拿大低北极地区(马尼托巴省丘吉尔)工作，建立一个“DNA条形码参考库”，从而可以使用DNA序列识别幼虫的生活期和小型隐蔽生物，这一事实促进了拟议的研究。这样的生命阶段通常构成了最丰富和多样化的生态系统要素，而以前的识别问题限制了我们进行群落分析的能力。最近的这项工作使生物多样性和群落结构的分析达到了几年前还不可能实现的规模。拟议中的研究将测试北极群落是否只是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来实现的。这项工作在规模上将是新颖的，涵盖了广泛的无脊椎动物群体、陆地和淡水栖息地、当地和区域地理规模以及多种营养水平。这一覆盖范围将允许评估所观察到的模式是系统特有的还是反映社区集合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.