Tactic-specific success in sperm competition

Sperm competition is a major force in sexual selection, but its implication s for mating-system and life-history evolution are only beginning to be und erstood. The well-known sneak-guard model predicts that sneaks will win in sperm competition. We now provide empirical confirmation of this prediction . Bluegill sunfish (Lupomis macrochirus) have both sneak (cuckolder) and gu ard (parental) males. Guards make nests, court females amid provide solitar y parental care for the embryos. Sneaks include small curkolders, which are termed 'sneakers: that dart in and out of nests in order to ejaculate betw een the spawning pair and larger cuckolders, which are termed 'satellites', that mimic females in order to ejaculate between the spawning pair. Using field behavioural data, genetic data and new mathematical models fur patern ity analyses, we show; for the first time to the authors knowledge, that sn eaks fertilize more eggs than guards during sperm competition. In addition, we show that sneakers are superior to satellites in sperm competition and, thus, that even among sneaks there are tactic-specific differences in comp etitive success.