Dissesrtation Research: A Cophylogenetic Analysis of Avian Hosts and their Parasites: Toucans (Aves: Piciformes) and Chewing Lice (Insecta: Pthiraptera)

我利用核和线粒体DNA序列重建了在生活史特征上不同的鸟类宿主类群（Ramphastos toucans）及其寄生的两个咀嚼虱属（Austrophilopterus和Menecanthus）的系统发育历史。本研究的目的是确定具有不同生态、行为和形态特征的寄生虫群体如何对相同的地理和栖息地扰动（寄主群体的多样化和物种形成）做出反应。我将通过叠加寄生虫及其宿主的系统发育来比较宿主和寄生虫的历史，以确定在生态、行为和形态上存在差异的寄生虫谱系是否对其宿主的物种形成事件有相似的反应。如果咀嚼虱生活史的差异是重要的，那么不同的寄生虫谱系在共同形成的程度上应该是不同的（平行物种形成）。然而，如果寄生虫谱系对宿主分离事件的反应相似，那么人们就会期望两种寄生虫谱系的系统发育树是一致的。通过这个简单的系统所获得的洞见，将有助于揭示更复杂的自由生物系统的物种形成模式。系统发育研究可以回答关于物种形成的重要问题。然而，系统发育学家面临的一个问题是，当研究自由生物时，他们往往缺乏关于研究生物栖息地和地理分布的历史信息。因此，系统发育研究中有用的第一步是重建这段历史。宿主及其寄生虫的共同发育研究通过将寄生虫的系统发育叠加到宿主的系统发育上来做到这一点。主群中的物种形成事件类似于生物地理替代事件（例如，当地理障碍将种群隔离导致物种形成时）。寄生虫的物种形成或缺乏物种形成代表了对宿主物种形成事件（替代事件）引起的地理和生态变化的反应。通过比较具有不同生态、形态和行为特征的寄生虫，我们将开始了解这些不同的生活史特征是如何影响物种形成过程的。

A cophylogenetic analysis of avian hosts and their parasites: toucans(Aves: Piciformes) and chewing lice (Insecta: Pthiraptera) I am using nuclear and mitochondrial DNA sequences to reconstruct the phylogenetic history of an avian host group (Ramphastos toucans) and two of its parasitic chewing louse genera (Austrophilopterus and Menecanthus), which differ in life history characteristics. The object of this study is to determine how parasite groups with different ecological, behavioral and morphological characteristics respond to identical geographical and habitat perturbations (diversification and speciation of the host group). I will compare host and parasite histories by superimposing the phylogenies of the parasites and their hosts to determine whether or not parasite lineages with differences in ecology, behavior, and morphology respond similarly to speciation events in their hosts. If differences in the life history of the chewing lice are important, the different parasite lineages should vary in their degrees of cospeciation (parallel speciation). However, ifparasite lineages respond to host isolation events similarly, then one would expect the phylogenetic trees of the two parasite lineages to be congruent. Insights gained via this simple system should shed light on patterns of speciation in more complex systems of free-living organisms. Phylogenetic studies can answer important questions about speciation. However, one problem faced by phylogeneticists is that, when studying free-living organisms, they often lack nformation about the history of the study organism's habitats and geographic distribution. Thus, a usefulfirst step in phylogenetic studies is to reconstruct this history. Cophylogenetic studies of hosts and their parasites do this by superimposing the parasite phylogeny onto the phylogeny of the host. Speciation events in the host group are analogous to biogeographic vicariant events (e.g., when geographic barriers islolate opulations leading to speciation). Speciation, or lack thereof, in the parasites represents a response to geographic and ecological changes caused by host speciation events (vicariant events). By comparing parasites with different ecological, morphological, and behavioral characteristics we will begin to understand how these different life history characteristics affect the process of speciation.