Systematics and Evolution of Body Size in Feather Lice (Phthiraptera: Columbicola)

这个项目将探索宿主-寄生虫系统中的共同物种形成，该系统由鸟类和它们特定于宿主的羽虱组成。当寄生虫物种形成(新物种的形成)与宿主物种形成同时发生时，共物种形成就发生了。反复的共物种形成导致寄主和寄生虫的进化树是彼此的镜像。共物种进化树的比较使人们能够识别宿主切换事件，在这种事件中，寄生虫从一个祖先宿主群“跳”到一个新的宿主群。鸟虱系统提供了一种模型，在该模型中，可以：1)通过比较基于DNA序列数据重建的进化树来识别主机切换事件；以及2)确定在什么条件下可能发生主机切换。具体地说，寄生虫是更有可能在密切相关的宿主物种之间“跳跃”，还是在身体大小或某些其他属性相似的宿主物种之间“跳跃”？宿主切换是一种重要的进化现象，与人类健康有着广泛的相关性。例如，HIV病毒似乎是由于宿主从非人类灵长类动物转移到人类而进化的。同样，人类疟疾可能是从禽类疟疾进化而来的。鸟类和虱子是一个模型系统，在这个系统中，结合涉及在不同种类的宿主之间移动特定宿主的寄生虫的切换的实验模拟，可以发现宿主切换的情况(见上文)。这样的实验不能在人体上进行，因此必须使用动物模型系统进行研究。该项目有一个重要的培训部分。一名博士生将参与这项工作的所有方面，几名本科生研究助理也将接受培训。

This project will explore co-speciation in a host-parasite system consisting of birds and their host-specific feather lice. Co-speciation takes place when parasite speciation (formation of new species) occurs in concert with host speciation. Repeated bouts of co-speciation result in host and parasite evolutionary trees that are mirror images of one another. The comparison of co-speciated evolutionary trees allows one to identify host-switching events, in which parasites "jump" from one ancestral host group to a new one. The bird-louse system provides a model in which it is possible to: 1) identify host-switching events by comparing evolutionary trees that have been reconstructed on the basis of DNA sequence data; and 2) determine under what conditions host switches are likely to occur. Specifically, are parasites more likely to "jump" between closely related species of hosts, or between species of hosts that are similar in body size or some other attribute? Host switching is an important evolutionary phenomenon with broad relevance to human health. For example, the HIV virus appears to have evolved as a result of a host switch from non-human primates to humans. Similarly, human malaria may have evolved from avian malaria. Birds and lice are a model system in which it is possible to uncover cases of host-switching (see above) in conjuntion with experimental simulations of switching that involve moving host-specific parasites among different species of hosts. Such experiments cannot be done with humans and must therefore be studied using animal model systems. This project has an important training component. A Ph.D. student will participate in all aspects of the work and several undergraduate research assistants will also receive training .