Do female bluethroats without extra-pair offspring have more MHC-compatible social mates?

Abstract Genes of the major histocompatibility complex (MHC) are crucial for adaptive immunity in jawed vertebrates, and theory predicts that there should be mate choice optimizing MHC constitution offspring. In a previous study, we demonstrated non-random female extra-pair males bluethroat ( Luscinia svecica ), yielding offspring was closer to an intermediate class II (MHCII) allele count than their within-pair halfsiblings. The present study tests whether social pairs with only young (WPY) brood, same population, had combined MHC-constitution presumed optimum, (EPY), corresponding pattern As expected, found WPY from pure WPY-broods were more MHC-optimal mixed broods, but broods (second year) males. Correspondingly, tendency brood MHC-compatible EPY when male young. Older have considerably larger testes males, higher sperm competitiveness could help them secure paternity own also they not MHC-compatible. other words, sexual conflict over paternity, females may likely realise preference paired male. possible fitness indicator, immune responsiveness injected antigen (PHA) elevated “the golden mean” MHCII count. Significance statement This contributes our understanding MHC-based mating systems, by showing bluethroats ) MHCII-compatible tend no is elucidates conflict, which older able override preferences prevent gaining through production. Studying systems occurs offers insight into genetic benefits choice, as contrast generally contribute sperm. Further, strict thorough genotyping scheme applied this enabled us demonstrate MHC-diversity species one highest II-diversity known date.