Article Abstract:
High levels of shared allozyme polymorphism have been found in three species of strongly differentiated congeneric clams of the Astarte genus. Biochemical genetic variation at 12 allozyme loci has been studied in the sympatrically occurring species from one location off the coast of Newfoundland, on the east coast of Canada. Time of speciation events seems consistent with the period proposed for rapid speciation in North Atlantic bivalves after major extinction event. Allozyme variation in the species was only related to allele frequency differences. No absolute, or fixed, differences were seen. Absence of diagnostic allelic differences is quite unusual.
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Article Abstract:
A research study was conducted to examine the patterns of gene flow at a fine scale with the St. Johns River drainage to test the predictions that the value within a drainage should be equal or greater than that among drainages. Four isozyme systems were used to characterize population structure and gene flow. The results showed no isolation by distance within two forks of the St. Johns drainage, but significant differentiations were apparent between two forks.
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Article Abstract:
A computer simulation suggests that mutation rather than selection is more likely to control the polymorphism and evolutionary rate of allozyme proteins. The range of models that can account for the variation in allozyme heterozygosity and genetic distance through type or intensity of selection is fairly narrow, whereas mutation rate can more easily explain the variation through a wider range of models.
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