The complexity of male reproductive success: effects of nutrition, morphology, and experience

Many studies have attempted to account for variation in male reproductive success by quantifying a single trait such as an ornament or a behavior, but male reproductive performance may be determined by a number of interacting traits. Although developmental nutrition is often a major determinant of adult body size and secondary sexual trait expression, other factors—such as residual shape variation and prior experience—may also exert independent effects on male reproductive success. Here, we studied how male sexual-trait expression, as manipulated by larval diet quality, and experience in direct male–male competition, affected male reproductive success in the sexually dimorphic neriid fly Telostylinus angusticollis. Among competing males matched by body size, individuals with relatively longer antennae (used as weapons) were more likely to win and also achieved matings faster. Unexpectedly, males reared on a poor larval diet and those that had previously lost in male–male combat appeared to invest more in some aspects of reproduction as indicated by a longer mating duration and a higher subsequent egg-hatching rate. Our findings demonstrate the complexity of male reproductive success, indicating that male developmental nutrition as well as morphological variation, and prior adult competitive experience interact in a complex manner to influence overall reproductive performance.