PATTERNS OF GENETIC DIFFERENTIATION AND CONSERVATION OF THE SLABSIDE PEARLYMUSSEL, LEXINGTONIA DOLABELLOIDES (LEA, 1840) IN THE TENNESSEE RIVER DRAINAGE

The restoration and recovery of imperiled mussel species willrequire the re-establishment of populations into historicallyoccupied habitats. The possible existence of genetic differentiationamong populations should be considered before inter-basin transfersare made. Eighty individuals of the federal candidate speciesLexingtonia dolabelloides were sampled from populations in theNorth Fork Holston, Middle Fork Holston, Clinch, Paint Rockand Duck rivers of the Tennessee River basin in the southeasternUnited States. We sequenced 603 base-pairs of a mitochondrialDNA gene (ND-1) and 512 base-pairs of a nuclear DNA gene (ITS-1).Analyses of molecular variation (AMOVA) values for both genesindicated that the majority of variation in L. dolabelloidesresided within populations (82.9–88.3%), with 11.7–17.1%of variation among populations. Haplotype frequencies differedsignificantly among populations for both genes sequenced. Clusteringof haplotypes in minimum-spanning networks did not conform stringentlyto population boundaries, reflecting high within-populationand low between-population variability. Maximum parsimony analysisdid not identify any population as a monophyletic lineage. AMantel test showed no significant correlation between geographicalstream distance and genetic distance, thus not supporting apattern of isolation-by-distance. Overall, results providedsupport to manage fragmented populations of L. dolabelloidesin the Tennessee River drainage as two management units (MUs),but did not provide evidence for the existence of ESUs followingpublished molecular criteria. (Received 26 October 2004; accepted 29 April 2005)