Genomic and Sex-Allele Diversity between Old and New World Honey Bee (Apis mellifera) Populations

Genomic and Sex-Allele Diversity between Old and

New World Honey Bee (Apis mellifera) Populations

Megan A. Taylor and Walter S. Sheppard

Washington State University, Department of Entomology, Pullman, WA 99164

The honey bee (Apis mellifera) is highly sensitive to inbreeding due to the nature of its haplodiploid mode of sex determination, controlled by the allelic composition of the complementary sex-determination (csd) gene.  Diploid individuals heterozygous for csd develop into females, haploid hemizygotes become males, while those homozygous for csd are culled during the larval stage.  The North American honey bee has suffered several genetic bottlenecks.  The number of sex-alleles in a population is directly related to colony fitness; too few sex-alleles drastically reduces brood viability, resulting in a weak colony.  Alternatively, if there are a variety of sex-alleles, homozygous drones are less likely to occur.  Diversity is maintained in two ways: through nonsynonymous mutations, selectively favoured within the hyper variable region of csd, and at a genome-wide scale.  Based on previous research, maintaining genome-wide diversity coupled with sex-allele diversity is likely the best defence against the deleterious effects of inbreeding.  To address this, we will initiate a comprehensive analysis of csd allele diversity and overall genetic diversity of Old and New World honey bee populations.  We will use primers specific to csd for the analysis of sex-allele diversity and microsatellite DNA markers to analyze variability at the genomic level.  This research will allow for the rapid and direct analysis of Old and New World honey bee population diversity.  Considering the enormous economical contribution honey bees provide agriculturally, such an analysis would provide a powerful genetic standard that breeders and researchers can use to improve colony fitness.