Allozyme variability and relatedness in six crayfish species.

A total of twenty-six allozyme loci were assayed in six crayfish species. Estimated mean heterozygosity was low (5.5 percent) for all species in comparison with the invertebrate average. The specific values, however, ranged from 2.9 percent to 8.3 percent. These crayfish estimates are consistent with estimates for other decapods where low heterozygosity is the rule. The consistency of low heterozygosity estimates in the order Decapoda suggests that its explanation may include both order specific differences such as low mutation or intracistronic recombination rates and species specific differences. A dendrogram, constructed using Nei's D, is in agreement with the morphological clustering.