POPULATION DIFFERENTIATION AND RACIAL ADMIXTURE IN THE AFRICANIZED HONEYBEE (APIS MELLIFERA L.).

To study the degree of interpopulational differentiation and racial admixture in Africanized honeybees, we collected worker bees from three regions of Brazil (the northeast, the state of Sao Paulo, and Porto Alegre) and from Uruguay and determined their genotypes for 10 enzyme loci. We also performed a morphometric analysis on forewing measurements of worker bees from the northeast and Porto Alegre regions of Brazil and from Paysandu, Uruguay. Comparative analysis of interpopulational heterogeneity snowed that there are significant differences, especially at the Mdh locus, among the populations from different regions. An increase in the frequency of the MdhB allele was observed from north to south, with predominance in the Uruguayan populations. A small component of interpopulational variability was detected in the populations studied. Racial admixture was calculated from information obtained for Mdh in Africa and Europe. The percentages of racial admixture differed slightly but significantly among Brazilian regions. The morphometric study based on canonical variables exhibited a similar pattern. The greater proportions of Apis mellifera adansonii alleles in the admixture may be explained by selection during the initial stage of migration of Africanized bees and by preferential mating between individuals of the same race. Differences in the proportions of A. m. adansonii alleles between regions indicate incipient populational differentiation of Africanized bees. We suggest that greater gene flow from the European races in the south of Brazil could be one of the causes of this phenomenon. © 1989 The Society for the Study of Evolution.