Document: CUR-3-47-1

Shifts in allele and genotype frequencies in zebra mussels, Dreissena polymorpha, along the latitudinal gradient formed by the Mississippi River.

ELDERKIN, C.L.* and P.L.KLERKS

University of Louisiana-Lafayette, Lafayette, LA USA ¹

Abstract:
Seven populations of zebra mussels were sampled along a latitudinal gradient in the Mississippi River. We scored 6 allozyme loci for all individuals using cellulose acetate gel electrophoresis. We analyzed the genetic data for Fis, Fit, and theta to estimate heterozygosity and genetic variation among populations, and we conducted a RXC G-test on allele and genotype frequencies. Following an estimation of Nei's genetic distance for each locus we determined the correlation between geographic distance and genetic distance using a Mantel test. Results show relatively large genetic differences between populations at the Lap locus (jackknife mean theta = 0.0673) and a significant amount of genetic variation between sites (bootstrap analysis 95% C.I. 0.037- 0.0005). Allele frequencies differed significantly among sampling sites at 2 of 6 loci (Lap p=0.001, Mpi p = 0.004), and we observed the same results for genotype frequencies (Lap p=0.003, Mpi p=0.001). Results of the Mantel test indicated a significant correlation between geographic distance and genetic distance at the Lap locus (Mantel's r p=0.03). We interpret these results indicating that 5 of 6 loci studied are in equilibrium in the Mississippi River populations, however non-random factors such as selection may be acting on the Lap locus or on genes nearby.

Keywords: zebra mussel, Dreissena polymorpha, allele, genotype frequency, allozyme electrophoresis

This abstract is being presented at: 10:30 AM in session:
Poster Session #9: Fish, Lakes, Streams and Wetlands.