Resource availability, mating opportunity, and sexual selection intensity influence the expression of male alternative reproductive tactics

The expression of alternative reproductive tactics can be plastic and occur simultaneously depending on cues that vary spatially or temporally. For example, variation in resources and sexual selection intensity is expected to influence the pay-off of each tactic and shape the decision of which tactic to employ. Males of the nuptial gift-giving spider Pisaura mirabilis can adopt three tactics: offering a genuine prey gift, a ‘worthless’ non-nutritious gift, or no gift. We hypothesized that resources and/or male body condition, and mating opportunity and sexual selection intensity, vary over the course of the mating season to shape the coexistence of alternative traits. We measured these variables in the field over two seasons, to investigate the predictions that as the mating season progresses, 1) males become more likely to employ a gift-giving tactic, and 2) the likelihood of switching from worthless to genuine gifts increases. Prey availability increased over the season and co-varied ...