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

劳舍9800876互惠是物种之间的生态相互作用，两个物种都从这种相互作用中受益。这个项目将评估蚂蚁和石斑豆之间花外花蜜介导的互惠互利的成本-收益框架的假设和预测。田间试验将评估四个假设：1)互惠互利的特性(花外花蜜)提供成本很高，2)花外花蜜通过减少被花蜜吸引的蚂蚁对食草动物的伤害而提供好处，3)成本和收益的平衡产生有利于中间最优的稳定选择，以及4)成本和收益的操纵应该改变选择性最优的价值。此外，该项目还将评估成本效益框架是否能够解释簇毛锦鸡儿花外花蜜性状的地理变异。将调查性状的地理变异，并将使用相互移植实验来检验种群之间的变异与不同选择最优的存在相一致的假设。互惠现象无处不在，但对其背后过程的理论和机制理解进展缓慢。在用于解释互惠关系进化的模型中，成本效益方法是理解互惠关系中所涉及的适应性特征进化的最一般和最合适的框架。这个项目将评估关于蚂蚁和美国东部一种常见的一年生植物Chamaecrista Fasculata(山豌豆)之间互惠互利的成本效益方法的假设和预测。这个项目的数据应该为未来关于互惠性状选择模式的讨论提供重要的经验基础。

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.