Bayesian Estimation of Host-Parasite Cospeciation

DEB-0075406John P. HuelsenbeckDr.罗切斯特大学的约翰·P·休尔森贝克（John P. Huelsenbeck）获得了一笔赠款，用于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。 他与Dr. Bret R.迪克讷大学的Larget和布鲁斯H.加拿大阿尔伯塔大学的Rannala博士对这项研究进行了研究。 寄生虫是依赖于另一种生物体（宿主）生存和繁殖的生物体，通常对宿主有害。通常，宿主和寄生虫的关联是高度特异性和古老的。 在这种情况下，可以通过检查相关宿主和寄生虫的亲缘关系（系谱）来推断宿主和寄生虫之间的关联历史。宿主和寄生虫的生殖基因完全或部分一致并不罕见，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，a、B和c是各自的寄生物物种（物种a寄生宿主A，依此类推），则三个宿主和寄生物的一致进化可能是（（A，B），C）和（（a，B），c）。寄主系统发育与种A和B是彼此最近的亲缘关系一致。类似地，与A和B相关的寄生虫（即，a和B）也是彼此最近的亲戚。这种模式与宿主和寄生虫的共同物种形成是一致的;宿主的物种形成事件导致相关的寄生虫通过异域物种形成而形成。通常，宿主和寄生虫的物种形成并不完全一致。此外，宿主和寄生虫的寄生性从来没有被正确地认识过。我们采用贝叶斯方法来推断宿主-寄生虫关联的历史。由NSF资助的这项研究提出了估计宿主转换，寄生虫物种形成和寄生虫灭绝的速率，同时适应宿主和寄生虫遗传学的不确定性。将使用称为马尔可夫链蒙特卡罗的数值技术来执行贝叶斯推断。

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..