Meeting Abstract

P2-137   -   Skull Asymmetry in Urban and Rural Virginia Opossums in Louisiana Abazajian, KA*; Rivera, G; Hedrick, BP; Tulane University, New Orleans, LA; Creighton University, Omaha, NE; Louisiana State University Health Sciences Center, New Orleans, LA k.abazajian@gmail.com

Through development, bilaterally symmetric organisms are canalized to resist genetic and environmental stressors and generate a developmentally stable, symmetric phenotype. Fluctuating asymmetry, random right-left perturbations from symmetry, is a proxy for quantifying developmental instability. Increased urbanization is often linked to environmental degradation (e.g., increased contaminants, pollution, habitat destruction), which could potentially lead to increased developmental instability in organisms given higher environmental stressors that organisms must overcome during development. However, previous work examining the link between increased fluctuating asymmetry and urbanization across a variety of vertebrate groups has produced mixed results. The Virginia opossum (Didelphis virginiana) is a common faunal constituent in urban settings in Louisiana and has even been considered to benefit from urbanization. Using two-dimensional (2D) geometric morphometrics of the crania and mandibles of a large sample of D. virginiana from across Louisiana, including both urban and rural individuals, we assessed whether individuals from urban or rural parishes had higher or lower asymmetry magnitudes. We found that fluctuating asymmetry was significant across our sample and accounted for 6.2% of total variation. Further, rural individuals had a higher magnitude of asymmetry than urban individuals. The rural individuals in our sample were also significantly larger than the urban individuals, though size and asymmetry magnitudes were not significantly correlated. Assuming the theoretical connection between magnitudes of asymmetry and developmental instability, this suggests that Virginia opossums are under less stress in urban environments compared with rural ones. Future work will incorporate three-dimensional (3D) geometric morphometrics allowing comparison between 2D and 3D based results.