Effects of contrasting demographic histories on selection at major histocompatibility complex loci in two sympatric species of tuco-tucos (Rodentia: Ctenomyidae)

• Autores: Cutrera, Ana Paula; Lacey, Eileen Anne; Mora, Matias Sebastian; Lessa, Enrique P.
• Año de publicación: 2010
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: CTENOMYS AUSTRALIS; CTENOMYS TALARUM; EXPANSION; POPULATION
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

To explore the impact of history on selection and genetic structure at functional loci, we compared patterns of major histocompatibility complex (MHC) variability in two sympatric species of ctenomyid rodents with different demographic backgrounds. Although Ctenomys talarum has experienced a stable demographic history, Ctenomys australis has undergone a recent demographic expansion. Accordingly, we predicted that MHC allele frequency distributions should be more skewed, differences between coding and noncoding regions should be less pronounced, and evidence of current selection on MHC loci should be reduced in C. australis relative to C. talarum. To test these predictions, we compared variation at the MHC class II DRB and DQA genes with that at multiple neutral markers, including DQA intron 2, the mitochondrial control region, and 8–12 microsatellite loci. These analyses supported the first two of our predictions but indicated that estimates of selection (based on ω-values) were greater for C. australis. Further exploration of these data, however, revealed differences in the time frames over which selection appears to have acted on each species, with evidence of contemporary selection on MHC loci being limited to C. talarum. Collectively, these findings indicate that demographic history can substantially influence genetic structure at functional loci and that the effects of history on selection may be temporally complex and dynamic.
Fil: Cutrera, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; Argentina
Fil: Lacey, Eileen Anne. University of California; Estados Unidos
Fil: Mora, Matias Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; Argentina
Fil: Lessa, Enrique P.. Universidad de la República; Uruguay