Allocation to mate guarding or increased sperm production in a Mediterranean wrasse

An excellent body of literature exists that examines sperm expenditure when males allocate only to sperm production. However, in many species, males c an also allocate energy to behaviors that influence sperm competition. We m odel whether males in sperm competition should allocate energy to mate guar ding or additional sperm production. Mate guarding is predicted to lead to greater reproductive success than increased sperm output, and mate-guarding males are not predicted to alter their allocation to sperm production with increasing sperm competition. Only when mate guarding is ineffective or gr eatly reduces sperm production are males predicted to allocate to sperm pro duction. in a Mediterranean wrasse Symphodus ocellatus, three male alternat ive reproductive behaviors coexist. While nesting males and satellites guar d mates to decrease sperm competition, sneaker males only compete ria sperm production. Sneakers produce four times as much sperm per spawn as either nesting males or satellites. As predicted by the: model, mate guarding bur not sperm production increased with increased risk of sperm competition in nesting males. We argue that this can be explained by nesting males allocat ing to mate guarding rather than sperm production. Considering allocation a mong behaviors that affect sperm competition enhances our ability to explai n and to predict sperm allocation patterns.