Abstracts (first author)
Sexually antagonistic genes in a natural population of African buffalo
The view is emerging that intralocus sexual conflict at so-called sexually antagonistic genes is a fundamental factor for the genetic architecture of fitness. However, we do not know of any study on a natural population which has been able to analyse sexually antagonistic genes directly. Here, we analysed heterozygosity-fitness correlations (HFC) using microsatellites to show the occurrence of sexually antagonistic genes in the African buffalo (Syncerus caffer) of Kruger National Park. Additional analyses provided new insights into the characteristics of these genes and the selection pressures involved. Expected heterozygosity increased in low body condition (LBC) females relative to high body condition (HBC) females, i.e. a negative HFC, while the opposite was observed in males, i.e. a positive HFC. Alleles with a high frequency in HBC relative to LBC females tended to have a low frequency HBC relative to LBC males. This observation indicates that the particular group of sexually antagonistic alleles linked to the studied microsatellites are beneficial to females and deleterious to males. Furthermore, sexual antagonism was strongest among the high frequency alleles, indicating that they are under positive selection. The sexually antagonistic alleles were dominant in females, indicated by LBC-HBC allele frequency differences among heterozygotes, but less dominant and possibly recessive in males. This sex-specific inheritance pattern may result in protected polymorphism. Pregnant females with relatively many sexually antagonistic alleles, expected to be beneficial to their daughters, were mostly carrying female foetuses, while those with relatively few sexually antagonistic alleles mostly male foetuses. Thus mothers try to improve the chances that sexually antagonistic alleles are transmitted to the sex they benefit. This shows that the genetic load of sexually antagonistic variation can be high enough to interfere with the sexual selection of good genes.