| a genetic discontinuity in a continuously distributed species: mitochondrial dna in the american oyster, crassostrea virginica. | restriction site variation in mitochondrial dna (mtdna) of the american oyster (crassostrea virginica) was surveyed in continuously distributed populations sampled from the gulf of st. lawrence, canada, to brownsville, texas. mtdna clonal diversity was high, with 82 different haplotypes revealed among 212 oysters with 13 endonucleases. the mtdna clones grouped into two distinct genetic arrays (estimated to differ by about 2.6% in nucleotide sequence) that characterized oysters collected north vs ... | 1990 | 1968412 |