Molecular Studies of Cospeciation Enhanced by Exhaustive Sampling and GIS Technology

Louisiana State University, Baton Rouge LA

Investigators

Abstract

ABSTRACT This project will continue an in-depth exploration of two organisms that have lived together for many millions of years, namely chewing lice (a group of parasitic insects) and their mammalian hosts (pocket gophers). Previous studies of this host-parasite system by the PI and colleagues have provided new insights into how organisms live in long-term symbiosis and has advanced our knowledge of rates of molecular change in insects versus mammals. This project will take a new and different approach to host-parasite studies by analyzing cospeciation at a previously unexplored scale augmented by use of GIS (Geographic Information Systems) technology. Analysis of cophylogeny (parallel speciation in the hosts and parasites) will use DNA sequences from both nuclear and mitochondrial genes. Recently developed methods will be used to compare rates of molecular evolution among genes, genomes, and species to identify gene-specific, genome-specific, and lineage-specific rate differences. GIS technology will be used to develop and test predictive distribution models (3ecological niche models2) for each species of pocket gopher and each species of louse examined in this study. Finally, this project will establish Louisiana State University (LSU) as an active node in the worldwide louse database (LouseBase), into which will be deposited all louse data generated in the course of this research. Data generated in the PI's studies of the gopher-louse system continue to be used widely in development of analytical methods and software for analysis of host-parasite systems (e.g., Huelsenbeck & Rannala, 1997; Huelsenbeck et al., 1997; and the programs COMPONENT and TREEMAP developed by Roderic Page). This work has also been featured in at least 8 books and textbooks, including Parasitology (Noble et al., 1989), A Functional Biology of Parasitism (Esch & Fernandez, 1993), and Evolution (Ridley, 1996). Thus, this work has reached a large number of graduate and undergraduate students. The proposed project has an explicit plan to involve students as collaborators in the research. This includes undergraduates, graduates, and postdocs at LSU, collaborators and their graduate students in Mexico, and undergraduate students at the University of Northern Iowa (UNI), which is a subcontractor on this project. Students at UNI will be trained in the fundamental, yet rapidly disappearing, skills of parasite taxonomy and identification, insect microscopy, and use of the digital microscopy imaging system for specimen documentation and morphological analysis. Students will also be exposed to the total breadth of the proposed research program through intensive, 10-day, summer workshops in the molecular lab at LSU. These workshops will not only train the students in the molecular techniques involved with the proposed research, but will also expose them to the workings of a larger research laboratory. This kind of exposure and experience is essential to encourage quality students to pursue careers in non-medical basic research.