Comparison of marker order and recombination rate between A. mellifera (European honey bee) and A. florea (red dwarf honey bee)

In sexually reproducing organisms meiotic recombination increases genetic offspring diversity, creating new genomes through chromosomal reconfiguration. The rate of recombination varies among and within species. They are exceptionally high in social insects, and the European honey bee (Apis mellifera) has the highest recombination rate known in multicellular eukaryotes. Three major, non-exclusive hypotheses have been proposed: High recombination may result from strong selection during domestication of the honey bee (1). High recombination may benefit division of labor (2) or disease resistance (3) by increasing genetic diversity among colony members. We compared the genomic recombination rate in Apis mellifera to that of the A. florea (the red dwarf honey bee). Compared to A. mellifera, this species is undomesticated, experiences a lower pathogen pressure, but exhibits a similarly complex division of labor. We screened 684 microsatellites from A. mellifera for polymorphism in A. florea. 44 polymorphic markers were detected and genotyped in a mapping population of 96 drones. Recombinational marker distances were calculated and genomic synteny assessed. Marker order was conserved in chromosome three but one possible inversion in chromosome twelve was identified. We found three intervals of significantly higher recombinational distances in A. florea and no intervals of significantly lower distances. We conclude that the high recombination rate in A. mellifera has not resulted from domestication and additional explanations are needed to explain that A. florea exhibits a higher recombination rate than A. mellifera. In general however, we support the link between complex division of labor and high recombination rate.