In internally-fertilizing animals, genitalia often evolve rapidly and may cause reproductive isolation that can give rise to new species. Female damselflies have plates at the top of their thoraxes that male damselflies latch on to in order to copulate. Males use on the ends of their abdomen to connect to the female's plates, forming a tandem. Once the tandem is created, and accepted by the female, copulation can begin. Male and female reproductive structures are species-specific, and fit together in a certain way that prevents most interbreeding among different species. However, two species, E. anna and E. carunculatum, occasionally interbreed in nature. Hybrid females' plates vary in both shape and the location of hair-like mechanoreceptors. The goal of this research is to examine the role of female plate morphology in the mating interactions of Enallagma damselflies. The first step is to quantitatively distinguish between purebred and hybrid species based on their plate morphology. To do so, cross-sectional data from micro-computed tomography scans is transformed into 3D models using the computer program Avizo. The plates are highlighted and segmented from a volume rendering of the entire thorax. Universal landmarks are then manually assigned to the computer-generated models, indicating unique regions of plate morphology and allowing for comparison of their 3-D shapes.
McMahon, M. (2016, April). Enallagma Plate Morphology and Mating Interactions. Poster session presented at the University of Oklahoma's Undergraduate Research Day, Norman, OK.