Fitness costs and benefits of sexual promiscuity in birds

In more than 75 % bird species, extra-pair paternity (situation, when at least one extra-pair young in the nest is sired by other male than a social partner of female) has been found. While male interset in attending extra-apir copulations (EPC) seems to be intuitive (more offsring sired), female motivation to engage in EPC are much less clear and obvious. Therefore, many adaptive hypotheses have been proposed to explain female proscuity. Adaptive hypothese state, that female benefits from this behaviour (higher genetic quality of offspring). The empirical evidence for such benefits, however, are missing and adaptive hypotheses remain a controversial topic. This has led to the emergence of non-adaptive hypothesis, that assume that EPC can evolve as a by-product of selection on other trait and female may not benefit from this behaviour. However, non-adaptive hypotheses are often neglected. Aim of this bachelor thesis is to take into account benefits and costs for both sexes and to point out some of the limitations of studies on EPC. Key words: Extra-pair paternity, extra-pair copulations, promiscuity, adaptive hypothesis, nonadaptive hypothesis, sexual selection, limitation of studie