Detecting population admixture in honey bees of Serbia

Honey bee workers were sampled across the Serbian territory during 2009-2010 from mostly non-migratory apiaries to determine the population structure of these bees using morphometric, genetic, and spatial information. A total of 134 bees were sampled, of which 77 were analysed using classical wing morphometrics and 122 bees were successfully analysed using 24 DNA microsatellite markers. A combination of methods including multivariate statistics and assignment tests (frequency-based and Bayesian) revealed the honey bees of this region to resemble the subspecies Apt mellifera macedonica, Apis mellifera carnica or hybrids of these two subspecies. Based on Bayesian assignment ('Structure') and spatial PCA, honey bees within the Serbian territory were composed of 56%-58% A. m. carica and 42%-44% A. m. macedonica. Spatial analysis showed the existence of a north-west to south-east dine in genetic differentiation. The bees in the north-west resemble A. m. carnica, while the bees in the south-east of the country are more similar to A. m. macedonica. Thus, the extent of A. m. macedonica within Serbia was greater than previously estimated. We define a line of hybridisation between A. m. carnica and A. m. macedonica within our study area. The dine of differentiation was still evident using a combination of genetic and spatial information, in spite of beekeeping activities including transhumance and breeding efforts.