F Villablanca | California Polytechnic State University at San Luis Obispo (original) (raw)
Related Authors
Université Montpellier 2 - Sciences et Techniques du Languedoc
Uploads
Papers by F Villablanca
DNA sequences for the gene encoding mitochondrial cytochrome oxidase in a group of rodents (pocke... more DNA sequences for the gene encoding mitochondrial cytochrome oxidase in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times. Chewing lice of the genera Geomydoecus and Thomomydoecus are obligate ectoparasites of pocket gophers (Fig. 1). Because the entire life cycle of these lice occurs exclu: sively in the fur of the host, and because different host species rarely interact, each species of louse is normally restricted to a single host species (1). As a result, there is close correspondence between gopher taxonomic boundaries and louse taxonomic boundaries (2). When viewed over large geographic and temporal scales, this restricted distributional pattern of chewing lice on pocket gophers has resulted in phylogenetic histories of lice and gophers that are remarkably similar (3-5). Although well-documented cases of host-parasite cospeciation are rare (3, 6), they are of interest because they permit comparative study of organisms with a long history of parallel evolution. The temporal component of parallel phylogenesis (in which lineages of hosts and their parasites speciate repeatedly at approximately the same time) permits examination of relative rates of evolution in the two groups by comparison of the amount of change each has undergone during their parallel histories. Because the life histories of hosts and their parasites are often profoundly different, studies of molecular evolution in hostparasite assemblages can help answer a broad spectrum of questions relating to the possible effects of generation time, metabolic rate, and other life history parameters on rates of mutation and evolutionary change. We examined DNA sequence variation in 14 species of pocket gophers and their chewing lice (7) to test for cospeciation and to investigate rates of molecular evolution
DNA sequences for the gene encoding mitochondrial cytochrome oxidase in a group of rodents (pocke... more DNA sequences for the gene encoding mitochondrial cytochrome oxidase in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times. Chewing lice of the genera Geomydoecus and Thomomydoecus are obligate ectoparasites of pocket gophers (Fig. 1). Because the entire life cycle of these lice occurs exclu: sively in the fur of the host, and because different host species rarely interact, each species of louse is normally restricted to a single host species (1). As a result, there is close correspondence between gopher taxonomic boundaries and louse taxonomic boundaries (2). When viewed over large geographic and temporal scales, this restricted distributional pattern of chewing lice on pocket gophers has resulted in phylogenetic histories of lice and gophers that are remarkably similar (3-5). Although well-documented cases of host-parasite cospeciation are rare (3, 6), they are of interest because they permit comparative study of organisms with a long history of parallel evolution. The temporal component of parallel phylogenesis (in which lineages of hosts and their parasites speciate repeatedly at approximately the same time) permits examination of relative rates of evolution in the two groups by comparison of the amount of change each has undergone during their parallel histories. Because the life histories of hosts and their parasites are often profoundly different, studies of molecular evolution in hostparasite assemblages can help answer a broad spectrum of questions relating to the possible effects of generation time, metabolic rate, and other life history parameters on rates of mutation and evolutionary change. We examined DNA sequence variation in 14 species of pocket gophers and their chewing lice (7) to test for cospeciation and to investigate rates of molecular evolution