Geographic variation of lactate dehydrogenase in the cricket frog, Acris crepitans

Geographic variation is present in what is probably the H subunit of lactate dehydrogenase in Acris crepitans, but not in the M subunit. Electrophoretically different products of two alleles occur in most of the species range. One allele predominates in eastern populations but becomes less common progressively westward from the Middle West. The other allele is the predominant one in the West and in a corridor leading from Nebraska to the western end of Lake Erie. The evidence from this locus suggests genetic continuity over the entire range.