Sexual Dimorphism in Flight-Related Structures of a Paper Wasp.

Male and female paper wasps (Vespidae: Polistinae) perform different behavioral roles. Thus, sexes may experience distinct selective pressures that may ultimately affect body size, shape, and proportions. We investigated this in the neotropical Polistes simillimus. We compared 100 males and 100 females using linear morphometrics, geometric morphometrics, and allometric analyses of head, mesosoma, forewing, and fore femur. Females were larger than males in all linear measurements. After correcting for body size, males exhibited wider heads, longer mesosomas, and longer fore femora, whereas females had longer heads. Positive allometry of mesosoma length was detected in males and negative allometry of fore femur length in females. Geometric morphometrics confirmed differences in both forewing (rounder in males, elongated in females) and mesosoma (stouter in males). These findings are consistent with the contrasting behavioral demands experienced by each sex; they also generate testable hypotheses regarding the evolution of flight performance in these insects.