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学中一个长期存在的难题。人们可能凭直觉认为，在每个主要的生态类别中，竞争会消灭所有的物种，只留下一个或几个合适的物种，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。这些系统是全社区分析的理想目标，因为与南方系统相比，它们的生物多样性较低。此外，许多合作者和我一直在低北极加拿大网站（丘吉尔，马尼托巴）工作了几年，建立一个“DNA条形码参考库”，它允许使用DNA序列的幼虫生命阶段和小的神秘生物体的识别，这一事实促进了拟议的研究。这些生命阶段通常构成最丰富和多样的生态系统元素，以前的识别问题限制了我们进行社区分析的能力。最近的这项工作使生物多样性和群落结构分析的规模在几年前是不可能的。拟议的研究将测试北极社区是否只是由能够在这种环境中殖民和生存的物种组成，或者是否有证据表明通过竞争和捕食等生物相互作用构建社区。这项工作将是新的规模，包括范围广泛的无脊椎动物群体，陆地和淡水栖息地，地方和区域的地理尺度，和多个营养水平。这一覆盖范围将允许评估所观察到的模式是否是系统特定的或反映更普遍的生态原则的社区集会。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辩论，包括生境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.