Morphological and Genetic Description of the Freshwater Mussel, Elliptio complanata (Lightfoot, 1786) in the Cape Fear River System, N.C.

Abstract

The purpose of this research is to provide a preliminary description of the morphological and genetic variation of a cosmopolitan freshwater mussel E. complanata from one North Carolina river system, Cape Fear River (CFR). Individuals from CFR were collected and compared with known specimens of E. complanata (topotype). Multivariate analyses, such as factor and discriminant analyses were utilized to differentiate the individuals based on thirty morphological shell landmarks. Genetic analyses involved the use of diversity estimates and cluster analyses based on cytochrome oxidase I (COI) sequence and Amplified Fragment Length Polymorphism (AFLP) fingerprint data. Factor analysis suggest that E. complanata from CFR maybe differentiated based on the thickness of posterior and anterior shell angles, and obesity of the shells. Significant differences between the CFR samples and topotypes were demonstrated by discriminant analysis of morphological data and by COI gene diversity estimates. This difference corroborated earlier work suggesting geographic delineation of E. complanata shell form. Genomic fingerprinting suggests further variation even within the topotypes. Phenotype of the topotypic materials seems to support this genomic variability. Heirarchical cluster analyses of morphometry and genetic data further showed different groups supporting earlier research suggesting high form variation within the E. complanata species.