Causes and Consequences of Reproductive Plasticity in the Seed Beetle, Callosobruchus maculatus

Competition for resources has direct effects on traits that can influence an individual’s reproductive success in competitive mating environments. When population density is high during development, competition for resources can reduce growth and body size at maturation, influencing resources available for reproduction. In this thesis, I investigate how the developmental environment affects plasticity in male reproductive traits, as well as the consequences of male reproductive plasticity on female reproductive behavior, in the seed beetle, Callosobruchus maculatus. My results show that increasing larval density causes male beetles to emerge small and transfer small ejaculates to females. However, small males transfer proportionally more sperm to females than large males developing at low larval density. This result suggests that developing male beetle larvae may use food limitation induced by high larval density as a cue that competition for mates in the adult environment is high. Therefore, maintenance of high sperm number may be the best strategy for high density males to mitigate fitness consequences associated with being small. Females mated to small males did not remate sooner or lay fewer eggs than those mated to large males. However, future work should consider how small males fair against large males in competitive mating scenarios.