Abstract
After the transition from a savannah to a desert about 10,000 years ago the isolated Saharan oases offer a unique case for studying the effect of population fragmentation and isolation over a period of many thousand years. We use the honeybee, Apis mellifera, as a test system because they are an abundant wild species in the African dry savannahs but are particularly sensitive to drift and bottlenecks in small isolated populations due to the small effective size resulting from male haploidy, the sex determination system and sociality. We compared the non-fragmented coastal population with the oases of Brak and Kufra using 15 polymorphic microsatellite loci assessing the mating frequency, colony density, gene diversity, and population differentiation. We found that the honeybee population of the remote oasis of Kufra is well isolated whereas those of the oasis of Brak and the coastal regions show genetic foot prints of introgression by commercial beekeeping. The isolated Kufra population showed no indications of inbreeding suggesting that the endemic population size is sufficient to ensure sustainable local survival.