No evidence for adjustment of maternal investment under alternative mate availability regimes

Using treatments that mimic high and low availability of reproductive males, it was found that female three-spined sticklebacks Gasterosteus aculeatus, previously shown to adjust their mate choices when male mates were rare, did not alter their reproductive investment strategies. These results suggest that plasticity in investment is perhaps limited by physiological requirements or dependent on relatively extreme mate availability regimes. The probability of becoming reproductive, number of clutches per season (per female), initial clutch size and mass and the timing of reproduction were all independent of the experience a female had with mate availability. This suggests that pre-copulatory plasticity in reproductive strategies may contribute more to variation in the strength and direction of sexual selection than reproductive investment in offspring.