Raw data for: Plastic male mating behaviour evolves in response to the competitive environment

Male reproductive phenotypes can evolve in response to the social and
sexual environment. The expression of many such phenotypes may also be
plastic within an individual’s lifetime. For example, male Drosophila
melanogaster show significantly extended mating duration following a
period of exposure to conspecific male rivals. The costs and benefits of
reproductive investment, and plasticity itself, can be shaped by the
prevailing socio-sexual environment and by resource availability. We
investigated these ideas using experimental evolution lines of D.
melanogaster evolving under three fixed sex ratios (high, medium and low
male-male competition) on either rich or poor adult diets. We found that
males evolving in high-competition environments evolved longer mating
durations overall. In addition, these males expressed a novel type of
plastic behavioural response following exposure to rival males: they both
significantly reduced and showed altered courtship delivery and exhibited
significantly longer mating latencies. Plasticity in male mating duration
in response to rivals was maintained in all of the lines, suggesting that
the costs of plasticity were minimal. None of the evolutionary responses
tested were consistently affected by dietary resource regimes.
Collectively, the results show that fixed behavioural changes and new
augmentations to the repertoire of reproductive behaviours can evolve
rapidly.