Synopsis for Setchell

The article’s main question is: “what is the influence of major histocompatibility complex (MHC) on patterns of reproduction in the mandrill? The study also looked into the possibility of whether or not the males had a reproductive advantage via either superior competitive ability or via female choice within-male MHC diversity. This study is innovative because this particular study contained a large dataset, involving reproduction over multiple years for a long-lived species. This study was also the first to demonstrate a reproductive advantage associated with MHC dissimilarity in a polygynous species with high levels of male-male competition. This study supported previous studies showing significantly higher rate of nonsynonymous than synonymous substitutions within the mandrill DRB.

This study was done on a large, semi-free-ranging population of mandrills, at the Centre International de Recherches Médicales, Franceville. Observations of the female reproductive status, births, injuries, and disappearance were made daily. DNA was extracted from blood samples obtained during annual captures of the colony for genetic analysis. MHC-DRB genotyping was also conducted for 155 of the population. The overall genetic similarity between genotypes of two individuals was estimated in order to determine whether reproduction was biased towards unrelated partners. Measures of MHC dissimilarity were also calculated for each potentially reproductive dyad in order to determine whether reproduction was biased towards partners with dissimilar MHC genotypes. Various statistical analyses were done in order to answer questions such as, “does overall genetic dissimilarity influence reproduction?” or “does male genotype influence reproduction?”

After genetic analysis, the results suggest that the MHC sequences are capable of providing resistance to pathogens, and thus might be the foundation of MHC- associated mate choice. The results showed that that pedigree relatedness, overall genetic dissimilarity, MHC dissimilarity and male genotype all influenced reproduction in this mandrill colony. Results also showed that male rank was by far the strongest influence on reproduction in males, with alpha males being 18 times more likely to sire a given offspring than nonalpha males.

The findings show that MHC-associated mate choice may be more widespread than previously thought. The findings also suggest that individual genetic characteristics in mandrills may be linked to male vigour and further studies can be taken on to investigate whether microsatellite heterozygosity or MHC diversity are linked to better condition or reduced susceptibility to disease.

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