MHC-associated mating strategies and the importance of overall genetic diversity in an obligate pair-living primate

Abstract

Mate choice is one of the most important evolutionary mechanisms. Females can improve their fitness by selectively mating with certain males. We studied possible genetic benefits in the obligate pair-living fat-tailed dwarf lemur (Cheirogaleus medius) which maintains life-long pair bonds but has an extremely high rate of extra-pair paternity. Possible mechanisms of female mate choice were investigated by analyzing overall genetic variability (neutral microsatellite marker) as well as a marker of adaptive significance (major histocompatibility complex, MHC-DRB exon 2). As in human medical studies, MHC-alleles were grouped to MHC-supertypes based on similarities in their functional important antigen binding sites. The study indicated that females preferred males both as social and as genetic fathers for their offspring having a higher number of MHC-alleles and MHC-supertypes, a lower overlap with female's MHC-supertypes as well as a higher genome wide heterozygosity than randomly assigned males. Mutual relatedness had no influence on mate choice. Females engaged in extra-pair mating shared a significant higher number of MHC-supertypes with their social partner than faithful females. As no genetic differences between extra-pair young (EPY) and intra-pair young (IPY) were found, females might engage in extra-pair mating to 'correct' for genetic incompatibility. Thus, we found evidence that mate choice is predicted in the first place by the 'good-genes-asheterozygosity hypothesis' whereas the occurrence of extra-pair matings supports the 'dissassortative mating hypothesis'. To the best of our knowledge this study represents the

Genetic diversity at neutral and adaptive loci determines individual fitness in a long-lived territorial bird

“…For example, Banks et al [55] described a positive correlation between heterozygosity at MHC-linked markers and survival in a long-lived mammal species (the mountain brushtail possum Trichosurus cunninghami). In males of fat-tailed dwarf lemur (Cheirogaleus medius) and grey mouse lemur (Microcebus murinus), MHC individual allelic diversity was associated with increased reproductive success [56]. Worley et al [20] observed a higher survival rate of MHC heterozygous individuals in red junglefowl (Gallus gallus) and also identified a particular MHC genotype strongly affecting survival probabilities.…”

An Evolutionary Approach Offers a Fresh Perspective on the Relationship Between Oral Contraception and Sexual Desire

“…MHC-disassortative mating occurs across fish, reptiles, birds, and mammals (Milinski, 2006;Penn, 2002;Roberts, 2009;Setchell & Huchard, 2010). In some socially monogamous birds and mammals (including primates), females not only choose to pair with MHC-dissimilar mates but are also more likely to engage in extra-pair copulations (evidenced by mixed paternity clutches) if their mate is relatively MHC-similar (FreemanGallant, Wheelwright, Meiklejohn, & Sollecito, 2006;Schwensow, Fietz, Dausmann, & Sommer, 2008); in so doing, they gain further genetic diversity in their offspring, with associated benefits in offspring health and survival (Foerster, Delhey, Johnsen, Lifjeld, & Kempenaers, 2003;Petrie & Kempenaers, 1998).…”

Semiochemical compounds of preen secretion reflect genetic make-up in a seabird species

“…Although most studies have focused on morphological and behavioural traits [1], evidence is accruing for multiple genetic criteria for mate choice [2,3]. Females may choose males with 'good genes', such as those with alleles or allele combinations increasing fitness [4,5] or with high heterozygosity [6][7][8].…”