Mitochondrial DNA variation in Moroccan and Spanish honey bee populations

The mitochondrial DNAs of 192 Moroccan and 173 Spanish honey bee colonies were characterized by a rapid test involving the restriction by DraI of a PCR-fragment of the COI-COII region. In Morocco, we found eight haplotypes, all characteristic of the African (A) lineage, suggesting that most if not all the maternal lineages of the colonies repeatedly imported from Europe over the last 150 years have not contributed mitochondrial genomes to the local population. Using two new genetic distances analogous to the shared allele distance defined for nuclear genes, we showed that Morocco was most probably colonized by two sublineages, one from the north-east and the other one from the south of the country and that the contact zone between them extends along both sides of the Atlas range. In Spain, we found eight haplotypes characteristic of lineage A (six in common with Morocco) and four of lineage M (the West European lineage). The distribution of haplotypes of both lineages forms a gradient with c. 10% of lineage M in the south of Spain (Seville) and up to 100% in the north (San Sebastian). Three hypotheses are presented to explain the large differences of haplotype frequencies between Moroccan and lineage A Spanish colonies: a non-Moroccan origin of lineage A in Spain, an ancient Moroccan origin or a recent Moroccan origin with a rapid shift of haplotype frequencies due to a founder effect.