Meeting Abstract
Sexual dimorphism in morphological traits, resulting from male-male competition or fecundity selection on females, has been well documented in many species. These differences between the sexes in morphology may have functional consequences, affecting the performance of either sex. While the dimorphism between the sexes is most often expressed in the adults, few studies have quantified whether the dimorphism of form and function is persistent throughout development. The goal of this study was to determine the difference in body size, foreleg size and kinematics of the feeding strike of a praying mantis throughout ontogeny and between the sexes. The feeding strikes of 8 ghost praying mantises (Phyllocrania paradoxa) from instar 4 (juveniles) to instar 8 (adults) were filmed at 1000 Hz. Several points were digitized on the mantises to obtain a set of angular and linear kinematics associated with the strike; as well as body and foreleg size. Using mixed models, I assessed the affect of instar, sex, prey position and their interactions on body and foreleg size, and principal components that characterize the angular and linear movements of the foreleg. I found similar trajectories of growth and kinematics between the sexes in juveniles, with angular kinematics decreasing and linear kinematics increasing. However, I found significant differences in foreleg size and linear kinematics in adults, with females exhibiting proportionally longer forelegs that are moved more and faster than males. These results suggest the differential growth of the foreleg between the sexes alters the biomechanics of the feeding strike, allowing for increasing linear kinematics despite decreasing angular kinematics during ontogeny. These patterns of form and function will be discussed in relation to life history evolution.
