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

Louisiana State University, Baton Rouge LA

Investigators

Abstract

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, if parasite 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 useful first 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.