ESTIMATING THE CONTRIBUTION OF LAYING WORKERS TO POPULATION FITNESS IN AFRICAN HONEYBEES (APIS-MELLIFERA) WITH MOLECULAR MARKERS

Two subspecies of honeybees, Apis mellifera capensis and A. m. scutell ata provide an ideal model to test for the significance of reproductiv e workers in natural populations of honeybees. Laying workers of A. m. capensis parthenogenetically produce female offspring (thelytoky) whe reas workers of the other subspecies produce male offspring (arrhenoto ky). By using a two allele marker system in both the mitochondrial (mt ) and in the nuclear (nuc) DNA, a deterministic population genetical m odel shows that through the differences in laying worker reproduction alone, dines of the mt and the nuc marker should be shifted. The stron ger the impact of laying workers the further should the capensis mt ty pe introgress into the scutellata population. The theoretical model is supported by empirical data from the hybrid zone between the two subs pecies. The nuc hybrid zone begins 200 km south of the mt hybrid zone indicating a significant impact of the laying workers on colony reprod uction.