Molecular Studies of Cospeciation in a Host-Parasite Assemblage

共同物种形成理论认为当两种生物 作为宿主和寄生虫错综复杂地联系在一起， 导致物种形成的一个成员对（主机）也将 导致其他成员（寄生虫）的物种形成。 主要 本研究的目的是检验 在一组啮齿动物宿主（囊地鼠）中的共同物种形成， 它们的体外寄生咀嚼虱 这将通过 研究人员比较了 宿主和寄生虫的基因序列差异 核酸分子。 到目前为止，研究人员已经使用了遗传数据， 独立的囊地鼠和咀嚼虱，以产生一个 囊地鼠的进化树和咀嚼树 虱子 当囊地鼠的分支结构和 经统计学方法比较， 发现它们非常相似 虽然这是必要的 证据来证明共同物种形成，这是不够的证据： 还必须证明，这些地区的物种形成事件 寄主和寄生虫几乎同时出现。 这一点可以通过比较 共存的主机和寄生虫，因为假设共同物种形成 事件 如果存在不等式， 大量的分子变化。 等量的变化将 构成了支持共同物种形成理论的有力证据 宿主-寄生物组合的最佳方式

The theory of cospeciation proposes that when two organisms are intricately associated as hosts and parasites, events that cause speciation in one member of the pair (the host) will also cause speciation in the other member (the parasite). The main purpose of this research is to test the hypothesis of cospeciation in a group of rodent hosts (pocket gophers) and their ectoparasitic chewing lice. This will be accomplished by the researchers comparing the amounts of evolutionary change in hosts and parasites based on amounts of sequence difference in nucleic acid molecules. To date, the researchers have used genetic data, gathered independently for pocket gophers and chewing lice, to produce an evolutionary tree for pocket gophers, and one for their chewing lice. When the branching structure of the pocket gopher and chewing louse trees was compared by statistical methods, it was found to be remarkably similar. Although this is necessary evidence to document cospeciation, it is not sufficient evidence: it must also be demonstrated that speciation events in these hosts and parasites occurred at approximately the same time. This can be tested by comparing amounts of molecular change in coexisting hosts and parasites since hypothesized cospeciation events. The theory will be falsified if there are unequal amounts of molecular change. Equal amounts of change will constitute strong evidence in support of the cospeciation theory for this host-parasite assemblage.