The effect of social environment on alternative mating tactics in male Endler's guppy, Poecilia wingei

Variation in sexual behaviour has both genetic (no experience or social contact needed) and environmental (based on individual experience) components. Within species, males can maximize their fitness during inter- and intrasexual selection in a variety of ways. This may lead to evolution of alternative male mating behaviours resulting in a dichotomy between courting/guarding and sneaking tactics. We used Endler's guppies to investigate (1) whether individual sexually naïve males have a preferred mating tactic (courting or sneaking), and (2) how male mating behaviour is affected by recent social history (male- or female-biased social environment). We found that individual males approached females by either courting or sneaking, even with no previous sexual experience. We further demonstrated that male sexual behaviour in standardized mating trials was strongly affected following exposure to a sex-biased social environment for 5 weeks. Males from female-biased social environments showed decreased mating effort overall compared to the baseline level (measured prior to assignment to a social environment treatment) but were more likely to court females rather than attempt sneak copulations. Males from male-biased social environments maintained a high level of mating effort and increased the rate of sneaking attempts compared to courtship displays. Our study highlights that both genetic and environmental sources of variation contribute to individual sexual behaviour. Current sexual behaviour was strongly modulated by recent social history, underpinning the importance of previous experience in the expression of sexual behaviour.