Abstract Alternative reproductive tactics often involve trade-offs between mating success and survival to sexual maturity, resulting in differential investment in shared traits driven by disruptive selection. Selection on intrinsic growth can lead to individuals optimizing mating success by delaying maturation, with others maturing precociously and at smaller sizes. Such trade-offs can continue post maturation and may differ between tactics or life histories. To examine differential investment in growth and reproduction, we explored relationships between body length and reproductive success in cuckolders, and compared body length and intrinsic growth in male (cuckolder vs parental) bluegill sunfish, Lepomis macrochirus. Reproductive success in cuckolders was highest at smaller (sneaker) and larger (satellite) body sizes. Cuckolders were larger than parentals in the first two years of life but not from year 3 onward, and growth trajectories varied significantly between cuckolder and parental life histories. Despite the early size advantage, cuckolders grew slower during early age transitions (1+→2+, 2+→3 + years), likely reflecting investment in sexual maturation. In subsequent years (3+→4 + and 4+→5+), cuckolders showed comparable growth to parentals despite parentals remaining immature. Cuckolders thus appear to persist through a phase of lower reproductive success at intermediate sizes by differentially investing in growth. Our results suggest that the alternative reproductive tactics in bluegill are driven in part by body size at age 1, with larger body size being a prerequisite for precocial maturation (adoption of the cuckolder life history). After initial investment in sexual maturation, cuckolders then re-prioritize growth during body sizes associated with lower reproductive success.
Cornwell et al. (Fri,) studied this question.