Dissertation Research: Genetic Diversity in Parthenogenetic Mites

发展对有性繁殖的起源和维持的理解目前被认为是进化生物学最重要的理论问题之一。为什么生物会继续“浪费”资源，并通过繁殖雄性来“牺牲”更快的种群增长？要想知道答案，需要研究相反的生活史策略--受精性孤雌生殖，这是一种从未受精卵中产生雌性后代的过程。先前的研究表明，甲螨分类群节肢动物总科包含已知的最大的孤雌生殖动物群体；其中许多家庭根本不包含有性物种。长期以来，人们一直认为，没有性行为，有机体就无法创造生存和进化所需的遗传灵活性；据推测，至少从长远来看，这是进化的“死胡同”。研究人员将使用现代方法来证明这些孤雌生殖螨类的种群确实有很大的遗传变异性。有了这些结果，再结合之前对这些螨类之间进化关系的研究，研究人员将表明，孤雌生殖并不总是消除有性繁殖中涉及的“浪费”的简单、进化的捷径。如果整个动物群体是在没有性行为的情况下进化的，那么未来对潜在机制的探索应该会间接地增加我们对有性繁殖本身的理解。

Developing an understanding of the origin and maintenance of sexual reproduction is currently considered one of the foremost theoretical problems of evolutionary biology. Why do organisms continue to "waste" resources and "sacrifice" more rapid population growth by the production of males? Learning the answers requires studying the opposite life-history strategy, thelytokous parthenogenesis, a process in which female progeny are produced from unfertilized eggs. Previous studies showed that the oribatid mite taxon Nothroidea contains the largest known grouping of parthenogenetic animals; many of the included families contain no sexual species at all. For a long time it has been thought that without sexuality an organism cannot create the genetic flexibility necessary to survive and evolve; supposedly, it is an evolutionary "dead-end" at least in the long term. The investigators will use modern methods to show that populations of these parthenogenetic mites do have substantial genetic variability. With these results, combined with previous studies of evolutionary relationships among these mites, the investigators will show that parthenogenesis is not always a simple, evolutionary short-cut to eliminate the "waste" involved in sexual reproduction. If whole groups of animals have evolved in the absence of sex, then the future search for the underlying mechanism should indirectly increase our understanding of sexual reproduction itself.