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

WPC0 2 B V T w# | x 10螺距z N x x x， x @；HP Laserjet （25-in-one, Network）PRS X X X X X X X X X X X X；HP Laserjet （25-in-one, Network）prsx1p1rn1h2is2 - J。本研究通过研究一组水生昆虫，Coenagrionidae豆娘科（蜻蜓目：钩翅目）的两属，来解释为什么物种对剧烈环境变化的反应不同。有些线虫的幼虫只在有鱼的池塘和湖泊中发现，而其余线虫的幼虫只在无鱼的池塘和湖泊中发现。相比之下，Ischnura物种在两种湖泊类型中都很丰富。本研究的目的是量化每种湖泊类型中豆豆蝇与其捕食者和猎物之间直接和间接相互作用的机制和相对优势，并比较这两个群落的结果。许多现有的理论通过假设在给定的营养水平上的所有物种都有相似的反应来探索剧烈的生态变化对群落结构的影响。然而，自然群落的比较表明，随着群落结构的变化，一些物种被灭绝和取代，而其他物种可以在广泛的生态条件下持续存在。这项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，表明它们对剧烈生态变化的敏感性（例如，与伴随的栖息地变化和气候变化的可比性）。

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).