Major histocompatibility complex variation in talas tuco-tucos: the influence of demography on selection

ANA PAULA CUTRERA; EILEEN LACEY

JOURNAL OF MAMMALOGY

Allen Press

Lugar: Lawrence; Año: 2006 vol. 87 p. 706 - 716

0022-2372

Although interactions between behavior, demography and genetic diversity have been studied extensively for neutral molecular markers, relationships among these variables remain poorly understood for loci that are subject to selection.The genes of the major histocompatibility complex (MHC) provide a particularly appropriate opportunity to examine the impact of selection on genetic structure; the high levels of polymorphism characteristic of these loci are thought to be maintained by selective pressures arising due to pathogen exposure and/or inbreeding depression, both of which may be influenced by behavior and demography. To explore interactions among population structure, selection, and genetic diversity, we compared levels and patterns of MHC variability in two demographically distinct populations of the talar tuco-tuco (Ctenomys talarum), a subterranean rodent that occurs in eastern Argentina. Specifically, we tested the prediction that selection on two class II loci (DRB and DQA) should be greater in the more dense, more inbred Mar de Cobo population. At both loci, allelism and heterozygosity were greater for Mar de Cobo than for Necochea. Similarly, for both loci, estimates of the intensity of selection (corrected for differences in effective population size) were greater for Mar de Cobo, as predicted based on demographic and behavioral differences between the study populations. Inter-locus differences in variability are examined with respect to the apparent function(s) of these genes, while inter-population differences in intensity of selection are evaluated with regard to the demonstrated behavioral and demographic differences between Necochea and Mar de Cobo.