Some social insects have proved to be adept invaders. Assisted by the international trade of the modern world, these species have spread far beyond the ocean and mountain barriers that once determined their distributions. In some cases, these range expansions have brought previously isolated sister species back into contact. What happens when such species try to mate?
We were interested in this question of interspecific mating in the case of two honey bees: the Western honey bee Apis mellifera and the Eastern honey (or hive) bee, Apis cerana. These species diverged from a common ancestor at least 6 million years ago, with A. mellifera native to Europe and Africa and A. cerana native to Asia and India. Western honey bees have of course since been transported, in association with agriculture, to every human-inhabited continent on earth. Eastern honey bees meanwhile, have been quietly expanding their range too in recent decades, invading both Papua New Guinea and Australia. Thus what were allopatric (or separate) ranges for millions of years have suddenly become partially sympatric.
Read entire article at: Sex between species: what happens when invasive honey bees meet the locals? — insectessociaux