Abstract:
Seven crayfish species from three genera of the subfamily Cambarinae
were electrophoretically examined for genetic variation at a total of
twenty-six loci. Polymorphism was detected primarily at three loci:
Ao-2, Lap, and Pgi. The average heterozygosities over-all loci for each
species were found to be very low when compared to most other invertebrate
species that have been examined electrophoretically.
With the exception of Cambarus bartoni, the interpopulation genetic
identities are high within any given species. The average interspecific
identities are somewhat lower and the average intergeneric identities are
lower still. Populations, species and genera conform to the expected
taxonomic progression. The two samples of ~ bartoni show high genetic
similarity at only 50 percent of the loci compared. Locus by locus
identity comparisons among species yield U-shaped distributions of
genetic identities.
Construction of a phylogenetic dendrogram using species mean genetic
distances values shows that species grouping is in agreement with
morphological taxonomy with the exception of the high similarity between
Orconectespropinquus and Procambarus pictus. This high similarity
suggests the possibility of a regulatory change between the two species.
It appears that the low heterozygosities, high interpopulation
genetic identities, and taxonomic mispositioning can all be explained on
the basis of low mutation rates.
