RESUMEN
Next-generation sequencing methodologies open the door for evolutionary studies of wildlife parasites. We used 2 next-generation sequencing approaches to discover microsatellite loci in the pocket gopher chewing louse Geomydoecus aurei for use in population genetic studies. In one approach, we sequenced a library enriched for microsatellite loci; in the other approach, we mined microsatellites from genomic sequences. Following microsatellite discovery, promising loci were tested for amplification and polymorphism in 390 louse individuals from 13 pocket gopher hosts. In total, 12 loci were selected for analysis (6 from each methodology), none of which exhibited evidence of null alleles or heterozygote deficiencies. These 12 loci showed adequate genetic diversity for population-level analyses, with 3-9 alleles per locus with an average HE per locus ranging from 0.32 to 0.70. Analysis of Molecular Variance (AMOVA) indicated that genetic variation among infrapopulations accounts for a low, but significant, percentage of the overall genetic variation, and individual louse infrapopulations showed FST values that were significantly different from zero in the majority of pairwise infrapopulation comparisons, despite all 13 infrapopulations being taken from the same locality. Therefore, these 12 polymorphic markers will be useful at the infrapopulation and population levels for future studies involving G. aurei. This study shows that next-generation sequencing methodologies can successfully be used to efficiently obtain data for a variety of evolutionary questions.
Asunto(s)
Ardillas Terrestres/parasitología , Ischnocera/genética , Repeticiones de Microsatélite/genética , Parasitología/métodos , Polimorfismo Genético , Animales , ADN/química , ADN/aislamiento & purificación , Infestaciones por Piojos/parasitología , Infestaciones por Piojos/veterinaria , Polimorfismo Genético/genética , Enfermedades de los Roedores/parasitología , Análisis de Secuencia/métodos , Análisis de Secuencia/veterinariaRESUMEN
The life-history traits of pocket gophers and their chewing lice suggest that there is little opportunity for transmission of parasites among pocket gophers, with the exception of transmission from mother to offspring. Herein, we test the hypothesis that lice are transmitted maternally by using an indirect approach that compares the distribution of louse populations to the distribution of mitochondrial DNA haplotypes in the pocket gophers. Comparison of the chewing louse distributions to the distribution of mtDNA haplotypes for the gophers revealed no significant concordance, and thus falsifies the maternal transmission hypothesis.
Asunto(s)
ADN Mitocondrial/química , Infestaciones por Piojos/veterinaria , Phthiraptera/genética , Enfermedades de los Roedores/transmisión , Animales , Electroforesis en Gel de Agar/veterinaria , Electroforesis en Gel de Almidón/veterinaria , Femenino , Haplotipos , Interacciones Huésped-Parásitos , Transmisión Vertical de Enfermedad Infecciosa , Infestaciones por Piojos/parasitología , Infestaciones por Piojos/transmisión , New Mexico , Phthiraptera/fisiología , Filogenia , Mapeo Restrictivo/veterinaria , Enfermedades de los Roedores/genética , Enfermedades de los Roedores/parasitología , RoedoresRESUMEN
DNA sequences for the gene encoding mitochondrial cytochrome oxidase I 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.
