Collaborative Research: Parasitism and Mutation in the Maintenance of Sex

异花受精的持续存在和广泛发生被广泛认为是自然选择进化理论最有趣的挑战之一。 一个有希望的理论是，通过创造遗传可变的后代，异花受精是一种减少寄生虫感染风险的方法，寄生虫进化为攻击共同的宿主基因型。 在这里，我们测试了这个理论的一些重要预测和假设。 具体目标有五个：（1）确定寄生虫是否可以在实验室条件下进化感染单个宿主基因型，以及这种反应是否需要在感染其他宿主基因型的能力方面进行权衡;（2）创造并实验感染杂交蜗牛，以确定感染的遗传基础;（3）延长一项为期七年的研究，研究宿主基因型的进化动态及其在自然种群中被寄生虫感染的情况;（4）测量突变积累的速率，作为对异花受精有助于消除有害突变的替代理论的检验;（5）为寄生虫假说提供直接的实验检验。 结果将感兴趣的流行病学家，作物植物病理学家和保护生物学家感兴趣的宿主遗传多样性和共同进化的寄生虫和病原体之间的相互作用。 这些结果也将引起进化生物学家的广泛兴趣，他们对自然选择对动植物繁殖策略的影响感兴趣。

The persistence and widespread occurrence of cross-fertilization is widely recognized as one of the most interesting challenges for the theory of evolution by natural selection. One promising theory is that, by creating genetically variable progeny, cross-fertilization is favored as a way to reduce the risk of infection by parasites that evolve to attack common host genotypes. Here we test some important predictions and assumptions of this theory. The specific objectives are five fold: (1) to determine whether parasites can evolve under laboratory conditions to infect individual host genotypes, and whether such a response entails a trade-off in ability to infect other host genotypes; (2) to create and experimentally infect hybrid snails to determine the genetic basis of infection; (3) to extend a seven-year study of the evolutionary dynamics of host genotypes and their infection by parasites in a natural population; (4) to measure the rate of mutation accumulation as a test of an alternative theory that cross fertilization helps eliminate harmful mutations; and (5) to provide a direct experimental test of the parasite hypothesis. The results will be of interest to epidemiologists, crop plant pathologists, and conservation biologists interested in the interplay between host genetic diversity and the effects of coevolving parasites and pathogens. The results will also be of wide interest to evolutionary biologists interested in the effects of natural selection on the reproductive strategies of plants and animals.