Females prefer good genes: Mate choice and MHC in tuco-tucos (Ctenomys talarum)

CUTRERA, ANA PAULA; FANJUL, MARIA SOL; ZENUTO, ROXANA RITA

Jornada; XXIV Jornadas Argentinas de Mastozoologia; 2011

Sociedad Argentina para el Estudio de los Mamiferos

The major histocompatibility complex (MHC) genes are one of the most suitable candidates for elucidating the genetic bases of mate choice in vertebrates, given the potential benefits in terms of immunocompetence that can be passed to the offspring through MHC-based mate choice. Females may choose males that possess particular MHC alleles, those with diverse MHC genotypes (good genes hypothesis) or are dissimilar compared to the female (compatibility hypothesis).  We evaluated mate choice in relation to MHC genotype in tuco-tucos. We used both lab (n=129) and field (n=112) analyses. Three lab tests were used to examine female preferences: (a) male odours, (b) confined males and (c) full contact with tethered males. Also, using the genotype of each mother caught in the field and her pups, we were able to infer the genotype/s of the potential sire for 22 litters. We investigated if 1) number of shared MHC alleles between male and female, 2) number of aminoacid differences between male MHC alleles, 3) number of aminoacid differences between female and male MHC alleles, and 4) MHC heterozygosity differed between preferred males and non-preferred males in the lab and potential sires and random males from the population in the field; and 5) if the distribution of MHC allele frequencies differed between preferred males and non-preferred males in the lab and potential sires and random males from the population in the field. In the lab, females preferred males carrying MHC alleles that differed in fewer aminoacids compared to non-preferred males. Concomitantly, possible sires in the field carried MHC alleles that differed in fewer aminoacids, were more heterozygous, and carried specific MHC alleles in comparison with random males in the population; thus providing more support to the “good genes” hypothesis. We discuss the implications of such a female mating strategy in the subterranean environment.