Does Stress Alter Competition Between Species and Thereby Affect Amphibian Communities in Aquatic and Terrestrial Habitats?

物种之间的相互作用，包括竞争、捕食和寄生，可以对决定自然群落的结构产生重要影响。因此，改变这种相互作用强度的因素可能有各种各样的影响。本研究的目的是研究水生系统中杀虫剂的存在如何改变两种无尾虫物种之间的竞争相互作用，从而改变群落组成。增加一个物种压力水平的因素可能会改变相互作用的强度，使一个物种比另一个物种具有优势。这种变化可能导致竞争力较弱的物种在当地灭绝。这一假设将通过在模拟自然条件的人工池塘中饲养蝌蚪来验证。这样就可以评价竞争和压力（由引入低水平杀虫剂引起）对幼虫发育和生存以及随后在陆地环境中生长和生存的单独和加在一起的影响。这项研究对了解两栖动物和其他动物如何对人类活动引起的栖息地变化（例如农业径流进入水生系统的化学物质）做出反应具有广泛的意义。两栖动物作为一个群体，在世界许多地方经历了显著的数量下降，但对导致这些下降的因素缺乏充分的了解。这项研究的结果可能至少有助于解释这些下降的部分原因。通过将基础生态学和应用生态学联系起来，这项研究将使人们更好地了解构成群落的生态过程，并为管理和保护生物多样性提供更好的方法。

Interactions among species, including competition, predation, and parasitism, can have important consequences for determining the structure of natural communities. Thus, factors that alter the strength of such interactions can have a variety of effects. The goal of this research is to examine how presence of an insecticide in aquatic systems can alter competitive interactions between two anuran species and thereby alter community composition. Factors that increase levels of stress on one species may alter the strength of the interaction and give one species an advantage over the other. Such changes could lead to local extirpation of the less competitive species. This hypothesis will be tested by rearing tadpoles in artificial ponds that simulate natural conditions. This will allow an evaluation of the separate and additive effects of competition and stress (caused by introduction of low-levels of an insecticide) on larval development and survival, and on subsequent growth and survival in the terrestrial environment. This research has broad implications for understanding how amphibians, and other animals, respond to habitat alterations that are caused by human activities (e.g. chemicals that enter aquatic systems from agricultural runoff). Amphibians have, as a group, experienced significant population declines in many parts of the world but a full understanding of factors that contribute to those declines is lacking. Results of this research may help explain at least some of those declines. By linking basic and applied ecology, this research will lead to a greater understanding of ecological processes that structure communities and provide better ways to manage and protect biological diversity.