Bayesian Estimation of Host-Parasite Cospeciation

约翰·P·惠森贝克博士。罗切斯特大学的John P.Huelsenbeck获得了使用贝叶斯统计方法研究寄生虫与其宿主物种之间的共同进化相互作用的资助。他正在与杜肯大学的布雷特·R·拉格特博士和加拿大阿尔伯塔大学的布鲁斯·H·兰纳拉博士合作进行这项研究。寄生虫是依赖另一种有机体(宿主)生存和繁殖的有机体，通常对宿主有害。通常情况下，宿主和寄生虫之间的联系是高度特定和古老的。在这种情况下，可以通过检查相关宿主和寄生虫的系谱(系谱)来推断宿主和寄生虫之间的关联史。寄主和寄生虫的系统发育完全或部分一致的情况并不少见，因为这两个群体是平行进化的。例如，如果A、B和C是宿主物种，而a、b和c是各自的寄生虫物种(物种a寄生宿主A，依此类推)，则三个宿主和寄生虫的一致系统发育可能是((A，B)，C)和((a，b)，c)。寄主系统发育符合种A和种B的近亲关系。同样，与A和B相关的寄生虫(即a和b)也是彼此最接近的亲戚。这种模式与宿主和寄生虫的同种关系是一致的；宿主中的物种形成事件导致相关寄生虫通过异地物种物种形成。典型地，宿主和寄生虫的系统发育并不完全一致。更重要的是，寄主和寄生虫的系统发育是不可能没有错误的。我们采用了贝叶斯方法来推断宿主与寄生虫之间的联系历史。这项由NSF资助的研究建议在考虑宿主和寄生虫系统发育的不确定性的同时，估计宿主切换、寄生虫物种形成和寄生虫灭绝的速度。将使用一种名为马尔科夫链蒙特卡罗的数值技术来执行贝叶斯推理。

DEB-0075406John P. HuelsenbeckDr. John P. Huelsenbeck of the University of Rochester, has been awarded a grant to use Bayesian statistacal methods to study coevolutionary interactions between parasites and their host species. He is collaborating with Dr. Bret R. Larget of Duquesne University and Dr. Bruce H. Rannala of the University of Alberta (Canada) on this research. Parasites are organisms that are dependent on another organism (the host) for their survival and reproduction and are typically harmful to the host. Often, the association of a host and parasite is highly specific and ancient. In such cases, it is possible to infer the history of association between hosts and parasites by examining the phylogeny (genealogy) of related hosts and parasites. It is not uncommon for the phylogenies of hosts and parasites to be fully or partially concordant as the two groups have evolved in parallel. For example, if A, B, and C are the host species, and a, b, and c are the respective parasite species (species a parasitizes host A, and so on), a concordant phylogeny of three hosts and parasites might be ((A,B),C) and ((a,b),c). The host phylogeny is consistent with species A and B being each others closest relatives. Similarly, the parasites associated with A and B (namely, a and b) are also each others closest relatives. This pattern is consistent with cospeciation of the hosts and parasites; a speciation event in a host causes the associated parasite to speciate via allopatric speciation.Typically, the phylogenies of hosts and parasites are not completely concordant. Morevoer, the phylogenies of the hosts and parasites are never known without error. We have taken a Bayesian approach to infer the history of host-parasite association. The research funded by NSF proposes to estimate rates of host-switching, parasite speciation, and parasite extinction while accommodating uncertainty in the phylogenies of hosts and parasites. A numerical technique called Markov chain Monte Carlo will be used to perform the Bayesian inference..