Abstracts (first author)
Avian malaria parasites and paternity in the blue tit
Monogamous bird species commonly adopt extra-pair mating as an alternative reproductive strategy. Since such behavior is potentially associated with very high costs in terms of desertion by the social male, it should be balanced by benefits, which may be either of direct or indirect origin. In the latter case, females may benefit from engaging in mating outside the pair bond if extra-pair males pass to the offspring genes of superior quality. One of the main determinants of individual quality is resistance to parasites. Therefore, if the social mate of the female is parasitized, she might be willing to seek resistance genes for her offspring through matings with other males. However, despite the strong theoretical prerequisites, robust empirical data verifying this prediction is lacking. Here, we test this hypothesis using infection status with malaria parasites as an index of genetic resistance. Blood parasites causing avian malaria (genus Plasmodium and Haemoproteus) are widespread among passerine birds and they may negatively affect fitness of the host by either reducing survival or reproductive success. We verified whether the occurrence of extra-pair offspring in the brood was related to infection status with avian malaria parasites of the social father in the wild blue tit (Cyanistes caeruleus) population characterized by relatively high frequency of extra-pair matings (40% of nests contain at least 1 extra-pair offspring) and approximately 60% infection rate with malaria parasites among adult males and females. Additionally, we examined whether the occurrence of extra-pair young is affected by infection status of the mother and the interaction between the infection status of both social parents.