Hi Eric,

In reply to your question there is one gene the csd gene with many variations as you can see another gene fem gene is implicated

The isolation of the sex determination locus in honey bees led to the identification of the complementary sex determiner (csd) gene (Beye et al., 2003) (Figure 3A). The csd gene encodes a potential splicing factor that exists in at least 15 allelic variants that differ on average in ~3% of their amino acid residues (Hasselmann and Beye, 2004). The csd gene product is necessary for female development, because inactivation of csd gene product in female embryos causes a full switch into male development (Beye et al., 2003). The target of the csd gene product was recently identified as the feminizer (fem) gene (Hasselmann et al., 2008) (Figure 3A). The fem transcript is splicing differently in males and females, so that only female cells have a functional fem gene product. In males, splicing introduces a stop codon into the fem coding sequence.

Going back to Gavin's point. Three isolated colonies have been found in an isolated part of Scotland that were surveyed for black bees in 1993-94. by the Stoakleys The colonies were checked again this year and still found to contain pure black bees. How have three colonies managed to survive for about 16 years in isolation?