Origin, evolution and conservation of the honey bees from La Palma Island (Canary Islands): molecular and morphological data

Genetic studies have shown a significant hybridization of local populations of <i>Apis mellifera</i> in the Canary Islands, as a consequence of queen importation. Since La Palma Island was a probable exception to this hybridization rule, a local honey bee Conservation Project was developed. As a first step, the genetic characterization of the population was performed with the scope of generating fundamental knowledge to correctly manage honey bee genetic resources. In this sense, the origin of the Canarian honey bee is at issue, since diverse morphological and genetic studies have shown it to be either African or European. In our study, 499 colonies from La Palma were analyzed using mitochondrial DNA, microsatellites and wing geometric morphometric data. Hybridization from the C evolutionary lineage was observed mainly at mitochondrial level, but this hybridization was focused on a restricted area and hybrid colonies were detected for replacement. All genetic and geometric morphometric results showed the Canarian honey bee clustered with Western European M branch, specifically with <i>A. m. iberiensis</i> subspecies, far from African ones. We concluded that the present Canarian honey bee gene pool would have originated most likely from human introductions from Portugal dating back to the conquest of the islands in the sixteenth century, although an ancestral natural colonization from Iberia cannot be ruled out. Results also showed that Canarian honey bees are genetically differentiated from <i>A. m. iberiensis</i>, probably due to micro-evolutionary processes, such as founder effects, bottleneck and local adaptation. Therefore, we propose the classification of these local populations as a differentiated ecotype of <i>A. m. iberiensis</i>. This study highlights the idiosyncrasy of the Canarian honey bee and the need to protect it, as it is a population that extends considerably the genetic diversity of M branch.