Body Shape Divergence in Invasive Round Goby

The round goby, Neogobius melanostomus, originally native to the Black and Caspian seas, was introduced into the Great Lakes via ballast water in the 1990’s. Since then, the species has spread to all of the Great Lakes, thriving in the Lake Michigan region and spreading to surrounding bays and rivers. Invasive species are considered to have a high evolutionary potential. Differences in environmental conditions between native and introduced ranges stimulate adaptive evolution. Multiple introductions of an exotic species can result in separate instances of founder effects, further increasing the chance of evolutionary change. A total of 267 round goby specimens were collected using hook and line from lake, harbor, or river sites around the Chicagoland area in the Summers of 2012 and 2013. Along with basic measurements of length and weight, geometric morphometrics were performed on each specimen, allowing detailed comparisons of morphology. A discriminant function analysis was performed using body shape data to determine if a specimen’s morphology was enough to correctly classify it by habitat. The results yielded 70.4% correct identification for lake vs. harbor specimens and 87.2% for lake vs. river specimens, indicating a significant difference in morphology of specimens by habitat