MICROSATELLITE VARIATION IN HONEY-BEE (APIS-MELLIFERA L) POPULATIONS - HIERARCHICAL GENETIC-STRUCTURE AND TEST OF THE INFINITE ALLELE AND STEPWISE MUTATION MODELS

Samples from nine populations belonging to three African (intermissa, scutellata and capensis) and four European (mellifera, ligustica, carn ica and cecropia) Apis mellifera subspecies were scored for seven micr osatellite loci. A large amount of genetic variation (between seven an d 30 alleles per locus) was detected. Average heterozygosity and avera ge number of alleles were significantly higher in African than in Euro pean subspecies, in agreement with larger effective population sizes i n Africa. Microsatellite analyses confirmed that A, mellifera evolved in three distinct and deeply differentiated lineages previously detect ed by morphological and mitochondrial DNA studies. Dendrogram analysis of workers from a given population indicated that super-sisters clust er together when using a sufficient number of microsatellite data wher eas half-sisters do not. An index of classification was derived to sum marize the clustering of different taxonomic levels in large phylogene tic trees based on individual genotypes. Finally, individual populatio n X loci data were used to test the adequacy of the two alternative mu tation models, the infinite allele model (IAM) and the stepwise mutati on models. The better fit overall of the IAM probably results from the majority of the microsatellites used including repeats of two or thre e different length motifs (compound microsatellites).