Experience does not alter alternative mating tactics in the burying beetle Nicrophorus vespilloides

Abstract

Alternative male mating tactics are widespread, but the cues that determine which tactic is adopted remain unclear. Size is commonly associated with alternative mating tactics, but it is not known how individuals gauge their size effectively, especially given that size is relative and frequency dependent. One possibility is that interactions with conspecifics are used to assess size, relative to potential competitors, and thus fine-tune tactics. Success in mating might also influence mating tactics given that this should indicate the potential availability of mates in the population. We tested these ideas in the burying beetle Nicrophorus vespilloides, examining whether individuals use the outcome of larval or adult interactions as cues to adjust the tactics used to acquire mates. Male N. vespilloides employ 2 tactics; search for a carcass, a resource required for reproduction, or release a pheromone (call) to attract a mate. Males are plastic in the amount of time they invest in each tactic, and in a related species (Nicrophorus orbicollis), male size influences the tactic adopted. We examine the potential effects of parental care, sibling competition, relative size within a brood, and adult experience of agonistic interactions and mating on tactic adoption. Absolute size was consistently the best predictor of calling rate, with smaller males calling more often than larger males. We suggest that the lack of a response to adult cues may reflect unpredictability in the occurrence of social interactions or stable size distributions in this population. Key words: alternative mating tactic, behavioral plasticity, conditional strategy, mate attraction, pheromone. [Behav Ecol]