ALLOZYME VARIABILITY AND RELATEDNESS IN 6 CRAYFISH SPECIES

A total of 26 allozyme loci were assayed in 6 spp. of crayfish [Orconectes virilis, O. propinquus, O. immunis, Cambarus bartonii, C. latimanus and C. robustus]. Estimated mean heterozygosity was low (5.5%) for all species in comparison with the invertebrate average. The specific values ranged from 2.9% to 8.3%. 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 [genetic distance], is in agreement with the morphological clustering.