Seasonal Variation in the Shape of Hetaerina americana

Abstract

The ability to fly strongly contributes to the success of insects. The adaptive nature of wing size and shape dictates much of the organism’s success flying, both short-term (food and mate acquisition) and long-term (persistence of the species in the environment). Members of Order Odonata (dragonflies and damselflies) are among the most efficient and iconic fliers in the animal kingdom, and wing shape is among many factors contributing to their flight success. The quantitative science of morphometrics is the study and analysis of shape. My study takes a morphometric approach to investigate variation in wing shape for Hetaerina americana, a common species of damselfly in North America. Specifically, I focus on variation in wing shape between damselflies emerging in mid-spring after a winter-long larval development versus those emerging in late summer after a warmer, summer-long larval development. Analyses revealed that for both fore wings and hind wings winter developer wing shapes differ significantly from summer developer wing shapes. Fore wings vary in shape more distinctly by season than do hind wings. Summer developer fore wings are broader than those of winter developers, and summer developer hind wings are narrower. This variation in wing shape may be a consequence of seasonal circumstances (shorter, warmer development with a higher larval metabolic rate), or reveal an adaptive strategy for flight in air of varying temperatures. This latter strategy would indicate a genetic plasticity capable of producing wing shapes adaptive to seasonal variation.