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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Population Distribution: Studies of Dispersal, Behavior, and Genetics II
HIERARCHICAL ANALYSIS OF GENETIC VARIATION IN FRESHWATER MUSSELS: COMPARISON OF ALLOZYMES AND DNA SEQUENCES.
D.M. Berg1, C.L. Elderkin2, A. Christian2, J.L. Metcalfe-Smith3, C.C. Vaughn4, and S.I. Guttman2. 1Department of Zoology, Miami University, Hamilton, OH 45011, 2Department of Zoology, Miami University, Oxford, OH 45056, 3National Water Research Institute, Burlington, ON, Canada L7R 4A6, 4Department of Zoology and Oklahoma Biological Survey, University of Oklahoma, Norman, OK 73019
We used a hierarchical design to examine partitioning of genetic variation of two species of freshwater mussels, Amblema plicata and Elliptio dilatata. This design allowed us to compare within-population, within-river, and among-river variation, measured using allozymes and DNA sequences (ITS-1, a nuclear locus and COI, a mitochondrial locus). Within-population variation, measured as heterozygosity, was similar between species. Both species exhibited significant within-river and among-river variation at allozyme loci; these values were greater for E. dilatata than for A. plicata. Preliminary analyses of DNA sequences identified few haplotypes for A. plicata (1 or 2 per population) and much greater diversity for E. dilatata (average of 5 per population at ITS-1). Cluster analysis of DNA sequences revealed no geographic structuring for A. plicata, while some evidence of geographic structure was found for E. dilatata. Thus, variation in E. dilatata was greater than or equal to that of A. plicata for both allozymes and DNA sequences, and at all levels of the hierarchy. While geographic structure was clearly evident in both species using allozyme analysis, DNA sequencing was much more variable. These results imply that the choice of methods for examining genetic variation may greatly influence conclusions regarding geographic structuring of such variation.
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