Evolution of Cheaters in an Obligate Mutualism: An Experimental Approach

0075944 pellmyr互惠的相互作用创造了被寄生虫利用的资源。这些寄生虫有时从互惠主义者进化而来，它们可以极大地改变相互作用的动态。专性互惠关系，如种子寄生传粉者和寄主之间的互惠关系，由于其简单性，为研究这种逆转提供了极好的模型。这项研究将使用一种最近进化的作弊丝兰蛾和它的授粉姐妹物种来测试第一个明确的场景，即任何义务互惠主义是如何进化的。在这种情况下，特定的生活史特征和生态环境将极大地促进这种类型的多样化。该项目有三个目标。首先，该研究将使用基于mtDNA和形态计量学数据的系统发育分析来检验关于在过去200 - 300万年中欺骗者、两种传粉者和它们的共同宿主之间不断变化的地理范围和共存历史的明确假设。其次，实验将用于验证产生骗子的传粉媒介具有必要的行为可塑性和产卵者形态，从而相对容易地从传粉媒介转变为骗子习惯的假设。第三，该研究将验证一个假设，即共存的传粉媒介之间的抵消出现物候现象促进了后来物种的欺骗进化。综上所述，该项目将把一个多物种共生置于其历史生物地理背景下，并使用一个最近的互惠共生中作弊进化的案例作为模板，通过实验来检验关于这个生态上重要的多样化过程的具体但可推广的假设。

0075944PellmyrMutualistic interactions create resources that are exploited by parasites. These parasites sometimes evolve from mutualists and they can greatly alter the dynamics of the interactions. Obligate mutualisms, such as those between seed-parasitic pollinators and their hosts, make excellent models for the study of such reversals because of their simplicity. This study will use a recently evolved cheater yucca moth and its pollinating sister species to test the first explicit scenario for any obligate mutualism of how it can evolve. In this scenario, specific life history traits and ecological context are suggested to greatly facilitate this type of diversification. The project has three objectives. First, the study will use phylogenetic analysis based on mtDNA and morphometric data to test explicit hypotheses about changing geographic ranges and history of coexistence between the cheater, two pollinators, and their shared host over the last 2-3 million years. Second, experiments will be used to test the hypothesis that the pollinator that gave rise to the cheater has requisite behavioral plasticity and ovipositor morphology to make the shift from pollinator to cheater habit comparatively easily. Third, the study will test a hypothesis suggesting that offset emergence phenology between coexisting pollinators facilitates the evolution of cheating in the later species. Taken together, this project would place a multi-species mutualism in its historical biogeographic context, and use a very recent case of evolution of cheating within that mutualism as a template to experimentally test specific but generalizable hypotheses about this ecologically important process of diversification.