DISSERTATION RESEARCH: Fitness consequences of variation in parasite-mediated selection on outbreeding in a natural population

绝大多数动物、植物和真菌是通过异交繁殖的，或者是通过两个个体之间的配子交换繁殖的。为什么这种繁殖方式如此普遍？克隆只需要一个个体，效率要高得多。进化生物学家已经为这个悖论奋斗了40年。红皇后假说认为，异种杂交之所以得以维持，是因为它促进了基因多样化的后代的产生，这些后代可以逃脱寄生。相比之下，克隆的后代在基因上与其父母相同，因此可能会受到已经适应感染其祖先的寄生虫的攻击。该提案将使用淡水蜗牛的自然种群和它们的绝育寄生虫来明确验证这一假设。这项研究将结合长期的实地观察和实验操作，以确定在寄生虫存在的情况下，异交蜗牛是否比克隆蜗牛更有优势。该结果将为自然界中生殖方式和遗传多样性的选择提供最广泛的评价之一。总的来说，该项目旨在了解遗传多样性在宿主种群中维持寄生虫抗性的力量。这些发现将对研究人员利用应用疾病系统解决人类和动物健康、作物管理和保护问题的工作产生影响。它们将特别有利于管理那些多样性正在减少（保护）或被操纵（农业）的种群。此外，研究人员致力于本科教育。他们提议将他们的工作转化为一个互动的实验室练习，指导本科生了解宿主和寄生虫之间相互作用的进化。

The vast majority of animals, plants, and fungi reproduce through outcrossing, or the exchange of gametes between two individuals. Why is this form of reproduction so common? Cloning, which only requires a single individual, is far more efficient. Evolutionary biologists have struggled with this paradox for 40 years. The Red Queen Hypothesis argues that outcrossing is maintained because it promotes the production of genetically diverse offspring that can escape parasitism. In contrast, cloned offspring are genetically identical to their parents and thus may be attacked by parasites that have adapted to infect their ancestors. The proposal will definitively test this hypothesis using a natural population of freshwater snails and their sterilizing parasites. The research will combine long-term field observations and experimental manipulations to determine if outcrossing snails gain an advantage over clonal snails in the presence of parasites. The results will provide one of the most extensive evaluations of selection on reproductive mode and genetic diversity in nature. Broadly, the project aims to understand the power of genetic diversity to maintain parasite resistance in host populations. These findings will bear upon the work of researchers using applied disease systems to address human and animal health, crop management, and conservation. They will particularly benefit the management of populations in which diversity is declining (conservation) or manipulated (agriculture). Moreover, the investigators are committed to undergraduate education. They propose to translate their work into an interactive laboratory exercise in which to instruct undergraduates in the evolution of interactions between hosts and their parasites.