Dissertation Research: Exploring Mechanisms of a Species Replacement in a Benthic Stream Community

自然群落内的格局是由非生物过程还是生物过程造成的，这仍然是一个重要的问题。在溪流中，生态学家传统上强调非生物因素，但越来越多的证据表明，生物相互作用构成了热带群落。不可否认，在俄亥俄州中部的溪流中，小龙虾物种的更替正在发生，这为严格测试控制底栖无脊椎动物分布和丰度的生物过程提供了一个独特的机会。将探索三种可能的机制：不同的繁殖成功、不同的竞争能力，特别是对鱼类捕食的不同脆弱性。具体地说，将确定捕食和竞争的直接和间接影响是否可以解释这种物种更替。实地调查、实验室实验和实地操作将阐明不同的大小、生长和栖息地使用如何影响这三种替代机制中的每一种。由于这种小龙虾替代品的持续性质，人们认为这将成为研究溪流中生物过程的模型系统。

Whether abiotic or biotic processes are primarily responsible for the patterns within natural communities remains an important question. In streams, ecologists have traditionally emphasized abiotic factors, but increasing evidence suggests that biotic interactions structure lotic communities. In central Ohio streams, a crayfish species replacement is undeniably occurring, providing a unique opportunity to test rigorously those biotic processes controlling benthic invertebrate distribution and abundance. Three potential mechanisms are to be explored: differential reproductive success, differential competitive ability, and particularly differential vulnerability to fish predation. Specifically, it will be determined if the direct and indirect effects of predation and competition can explain this species replacement. Field surveys, lab experiments, and field manipulations will clarify how differential size, growth, and habitat use influence each of these three alternative mechanisms. Because of the ongoing nature of this crayfish replacement, it is believed that this is to be a model system for studying biotic processes in streams.