Allozyme variation, population structure, and sibling species in Aphis pomi

Apterous apple aphids (Aphis pomi de Geer) collected from several southern Ontario orchards in several seasons were studied electrophoretically for 17 enzyme and 2 protein loci. Sixteen loci proved monomorphic. The remaining three showed a strong association among loci; all individuals that are homozygous for the fast allele of glutamate oxaloacetate transaminase (Got) also have no esterase-1 activity (presumably being fixed for a null allele) …