REU: Parasite Communities in the Wyoming Ground Squirrel

在过去的几年里，关于竞争是群落结构的主要决定因素的争论对生态文献做出了不同的贡献。在自然群落的实证工作，提供明确的数据来支持任何一个论点是罕见的。所提出的实地和实验室实验将证明在寄生虫行会中存在或不存在竞争。结果将显示几个物种是否可能同时占据“同一生态位”。此外，还将收集有关宿主与寄生虫相互作用的充分数据，以确定这种关系是寄生的还是共生的。这一提议将检验以下假设：(1)怀俄明州地松鼠(spermoophilus elegans elegans)-球虫（Eimeria）的关联是一个长期共同进化历史的产物，“寄生虫”确实与动物对宿主适应性的影响是共生的；(2)寄生虫在宿主中不引起免疫反应；(3)寄生虫物种与宿主之间不存在生态位分配。有人提出，这些寄生虫已经进化到利用短暂的资源，快速再生的肠上皮细胞，它们是逃亡物种的缩影。该提案将通过一个地松鼠及其寄生虫的模型系统来测试社区层面对“逃亡”物种控制的缺乏。这是第一次对宿主-寄生虫相互作用进行如此长时间的长期实验研究，或者在自然种群中使用如此大的样本量。

Over the last few years the controversy about competition as a major determinant of community structure has made a variable contribution to the ecological literature. Empirical work in natural communities which provides unambiguous data to support either of the arguments is uncommon. The experiments, field and lab, which are proposed will demonstrate the existence or absence of competition within a guild of parasites. Results will show if it is possible for several species to occupy the "same niche" at the same time. In addition, sufficient data will be gathered on host parasite interactions to determine if the relationship is parasitic or commensal. This proposal will test the hypothesis that: (1) the Wyoming ground squirrel (Spermophilus elegans elegans)-Coccidia (Eimeria) association is the product of a long coevolutionary history and that the "parasites" are really commensals with animal effects on host fitness, (2) the parasites elicit no immune response in the host, and (3) there is no niche partitioning among parasite species with the host. It is proposed that these parasites have evolved to use ephermeral resources, the quickly regenerating cells of the intestinal epithelium, and they are the epitome of fugitive species. The proposal will test the lack of community-level controls on "fugitive" species using a model system of ground squirrels and their parasites. This is the first long-term experimental study on host-parasite interactions of this duration or with such a large sample size in a natural population.