Dissertation Research: The Evolution of Mutualism and Cost-Benefit Analysis: Selection on Extrafloral Nectar Traits of Chamaecrista Fasciculata

Rausher 9800876 互惠是物种之间的生态相互作用， 物种从相互作用中受益。 该项目将评估 成本效益框架的假设和预测 花外花蜜介导的蚂蚁与决明属植物的互惠共生 fasciculata，parabelia豌豆。 一个实地实验将评估四个 假设：1）互利特性（花外花蜜）是昂贵的， 提供，2）花外花蜜通过减少 食草动物的损害蚂蚁吸引到花蜜，3）平衡， 成本和收益产生稳定的选择， 中间最佳，和4）操纵成本和收益应 改变选择最优值。 此外，该项目 将评估成本效益框架是否可以解释地理 C.花外花蜜性状的变异束状。 地理 将调查性状的变化，并假设 种群间的变异与 不同的选择性最优将使用相互移植进行测试 实验 互利主义无处不在，但理论和机械 对它们背后的过程的理解进展缓慢。 在用来解释互惠进化的模型中， 成本效益方法是最普遍和最适当的 理解适应性特征进化的框架， 互惠互利 该项目将评估假设和预测 关于蚂蚁和蚂蚁之间的互利关系的成本效益方法 决明：美国东部一种常见的一年生植物，决明属 fasciculata（豌豆）。 该项目的数据应提供 这是今后讨论经济增长模式的一个重要经验基础。 互利性状的选择。

Rausher 9800876 Mutualisms are ecological interactions between species in which both species benefit from the interaction. This project will evaluate the assumptions and predictions of the cost-benefit framework for the extrafloral nectar-mediated mutualism between ants and Chamaecrista fasciculata, the partridge pea. A field experiment will evaluate four assumptions: 1) the mutualistic trait (extrafloral nectar) is costly to provide, 2) the extrafloral nectar provides a benefit through reduction of herbivore damage by ants attracted to the nectar, 3) the balance of costs and benefits produces stabilizing selection favoring an intermediate optimum, and 4) manipulation of costs and benefits should change the value of the selective optimum. In addition, this project will assess whether the cost-benefit framework can explain geographic variation in extrafloral nectar traits in C. fasciculata. Geographic variation in the trait will be surveyed, and the hypothesis that variation between populations is consistent with the presence of different selective optima will be tested using a reciprocal transplant experiment. Mutualisms are ubiquitous, but theoretical and mechanistic understanding of the processes that underlie them has progressed slowly. Of the models that have been used to explain the evolution of mutualisms, the cost-benefit approach is the most general and the most appropriate framework for understanding the evolution of adaptive traits involved in mutualisms. This project will evaluate the assumptions and predictions of the cost-benefit approach in regard to a mutualism between ants and a common annual plant of the eastern United States, Chamaecrista fasciculata (the partridge pea). Data from this project should provide an important empirical basis for future discussion of the pattern of selection on mutualistic traits.