Sexual selection in sticklebacks in the field: correlates of reproductive,mating, and paternal success

Male sticklebacks display multiple ornaments, and these ornaments have been shown to be preferred by females in laboratory experiments. However, few f ield data exist, and it is not known whether these preferences are simultan eously or sequentially operative in a single population. We report correlat es of reproductive success in two stickleback populations that differ in th eir ecology, over several periods within their breeding season. In both pop ulations larger males had higher reproductive success, but not in all perio ds of the breeding season. Reproductive success increased with redness of t he throat only in the Wohlensee population, and only in one period chat was characterized by low average success. In the Wohlensee population, the par asitic worm Pomphorhynchus laevis is abundant, and reproductive success dec reased with the presence of the parasite. In the Roche population, males wi th nests concealed in a plant had higher mating success. These nests were l ess likely to fail, suggesting that females preferred to spawn in concealed nests because of higher offspring survivorship. The different sexual trait s appear to reveal different aspects of male quality (multiple message hypo thesis): females probably find large males attractive because of their high er paternal quality, but it seems more likely that red males are prefer-red for better genetic qualities. Females also discriminate on territory quali ty, and male traits may be important in competition for these territories. The correlates of reproductive success were not consistent during the seaso n, probably due to changes in the availability of ripe females. Such fluctu ating selection pressures will contribute to the maintenance of genetic var iation in sexual traits.