Biophysical and Behavioral Agents of Natural Selection in a Hybrid Zone

杂交区的结构取决于自然选择和扩散的相互作用。 使用不同形式的自然选择的简单模型已经产生，以解释结构和混合区的维护。 然而，实地研究表明，自然选择可能非常复杂，通过简单的模型无法了解杂交区。 有必要确定自然选择的动因及其运作的生态环境，以了解杂交区是如何形成和维持的。 本研究旨在确定两种海洋贻贝之间形成的混合区中的选择力。 从以前的补助金的结果表明，这两个物种不同的生理能力，以容忍升高的淤泥。 一种可能的适应上升的淤泥是增加流动性，使动物可以移动，避免窒息。 这种适应可能是有害的，在开放的海岸环境中，淤泥浓度低，贻贝可能会被驱逐暴露在增加的波浪作用。 移动的较多的贻贝如果迁移到贻贝床的顶部或迁移到它们更可能被驱逐的其他位置，则可能暴露于更大的波浪作用。 这项研究将测试的假设，这两个品种的贻贝不同的行为适应淤泥，这些差异导致强大的自然选择对更多的移动的物种在开放的海岸环境。

The structure of hybrid zones depends on the interaction of natural selection and dispersal. Simple models using different forms of natural selection have been generated to explain the structure and maintenance of hybrid zones. However, field studies have shown that natural selection can be very complex and that an understanding of hybrid zones cannot be obtained through simple models. It is necessary to determine the agent of natural selection and the ecological circumstances under which it operates to understand how hybrid zones are formed and maintained. This study proposes to determine the selective forces operating in a hybrid zone formed between two species of marine mussels. Results from a previous grant demonstrated that the two species differed in their physiological capacity to tolerate elevated silt. One possible adaptation to elevated silt is increased mobility so that the animal can move and avoid smothering. This adaptation may be detrimental in open coast environments where silt concentrations are low and mussels may be dislodged by exposure to increased wave action. Mussels that are more mobile may be exposed to greater wave action if they migrate to the top of mussel beds or into other locations where they are more likely to be dislodged. This study will test the hypothesis that these two species of mussels differ in their behavioral adaptations to silt and that these differences result in strong natural selection against the more mobile species in open coast environments.