Evolution of Cheaters in an Obligate Mutualism: An Experimental Approach

Pellmyr相互作用创造被寄生虫利用的资源。这些寄生虫有时是从互助者进化而来的，它们可以极大地改变相互作用的动态。专性互惠，例如种子寄生传粉者和它们的寄主之间的互惠，因为它们的简单性，成为研究这种逆转的极好模型。这项研究将使用最近进化的一种作弊丝兰蛾和它的授粉姐妹物种来测试它如何进化的任何强制性互惠关系的第一个明确的场景。在这种情况下，特定的生活史特征和生态环境被建议极大地促进这种类型的多样化。该项目有三个目标。首先，这项研究将使用基于线粒体DNA和形态测量学数据的系统发育分析来测试关于欺骗者、两个传粉者和它们共同的宿主在过去200-300万年里变化的地理范围和共存历史的明确假设。其次，实验将被用来检验这样的假设，即产生欺骗者的传粉者具有必要的行为可塑性和产卵者的形态，从而相对容易地从传粉者转变为欺骗者的习性。第三，这项研究将检验一种假设，即共存传粉者之间抵消羽化物候有助于在较晚的物种中进化欺骗行为。综上所述，该项目将把多物种互惠放在其历史生物地理背景下，并使用最近在该互惠中作弊的进化案例作为模板，以实验测试关于这种生态上重要的多样化过程的具体但可概括的假说。

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.