Trade-offs and Community Structure Along Environmental Gradients: An Experimental and Comparative Approach

WPC0 2 B V 不 W #|X 10节距 z N x x x， X @ ; HP Laserjet（25合一，网络） HPLASEII.PRS X t 4 P RN h 0 IS 2 4 V N W #|X 10节距 z N x x x， X @ ; HP Laserjet（25合一，网络） HPLASEII.PRS X t 4 P RN h 0 IS 2 - J . 小行星9307033 本研究通过对一组水生昆虫--蜻蜓目（Odonata：Zygoptera）的两个属--Coenagrionidae豆娘的研究，探讨了物种对剧烈环境变化的反应为何不同。 一些Enallagma物种仅在有鱼的池塘和湖泊中发现幼虫，而其余的Enallagma物种仅在无鱼的池塘和湖泊中发现幼虫。 相比之下，Ischnura物种丰富的两个湖泊类型。 本研究的目标是量化的机制和相对优势，直接和间接的相互作用豆娘，他们的捕食者，他们的猎物在每个湖泊类型，并比较这些结果的两个社区。 目前的许多理论都假设所有物种在给定的营养水平上的反应都是相似的，以此来探讨生态变化对群落结构的巨大影响。 然而，自然群落的比较表明，虽然一些物种被淘汰，并取代群落结构的变化，其他物种可以在广泛的生态条件下持续存在。该研究将对保护生物多样性产生重要影响，通过确定物种的关键特性，表明它们对剧烈的生态变化的敏感性（例如，与伴随的栖息地改变和气候变化相比）。

WPC0 2 B V T W #| x 10 pitch z N x x x , x @ ; HP Laserjet (25-in-one, Network) HPLASEII.PRS X t 4 P RN h 0 IS 2 4 V N W #| x Courier 10 pitch z N x x x , x @ ; HP Laserjet (25-in-one, Network) HPLASEII.PRS X t 4 P RN h 0 IS 2 - J . 9307033 McPeek This research addresses why species differ in their responses to dramatic environmental changes by studying a group of aquatic insects, the Coenagrionidae damselflies (Odonata: Zygoptera) in two genera. Some Enallagma species are found as larvae only in ponds and lakes containing fish, while the remaining Enallagma species are found as larvae only in fishless ponds and lakes. In contrast, Ischnura species are abundant in both lake types. The objectives of this research are to quantify the mechanisms and relative strengths of direct and indirect interactions among damselflies, their predators, and their prey in each lake type and to compare these results for the two communities. many current theories explore the consequences of dramatic ecological changes to community structure by assuming that all species at a given trophic level respond similarly. However, comparisons of natural communities show while some species are extirpated and replaced as community structure is changed, other species can persist over wide ranges of ecological conditions. %%% The study will have important ramifications for conserving biodiversity, by identifying key properties of species indication their sensitivity to dramatic ecological changes (e.g, comparable to those accompanying habitat alterations and climate change).