Years ago, we learned that honey bees developed in Africa, then spread north and evolved into different subspecies. It is not surprising that the bee could adapt to the much colder northern climates – you don’t even need to accept evolutionary science to see how that might work. With moderate genetic mutations from damaging gamma rays or localized environmental hazards, changes occur. With vast and rapidly reproducing populations such as bees, some mutations inevitably are beneficial to survival. In the presumed case of bees out of Africa, as bees slowly migrated north, the most cold-hardy descendants reproduced. From Africa’s adansonii or scutellata (or their earlier representatives), descendants became Europe’s mellifera, ligustica, caucasica, and carnica. These are the black bee, the Italian, the Caucasian, and the Carniolan respectively. But this simplified collection leaves out a host of other non-African races – the Middle Eastern anatoliaca, syriaca, lamarckii and meda, for some examples.
Did the honey bee originate in Africa? The out of Africa idea was developed a hundred years ago and was based on phenotypical traits (physically visible and measurable characteristics) and the assumed effects of geography and climate on the bees’ divergences. But now we are not so certain. In 1992, mitochondrial DNA (mtDNA) was analyzed from 68 colonies in ten different regions. The scientists found 19 different subspecies represented by the mtDNA. On the basis of their best fit “Tree of Life” model, they clumped these into three different clades, or branches. These lineages are African, Mediterranean, and European. But these scientists had a surprising result. They found that the oldest mitochondria could be traced to the Mediterranean branch while the African branch showed greater change. They surmised that the original dispersion of honey bees was from the Middle East: “The pattern of spatial structuring suggests the Middle East as the centre of dispersion of the species.” This result, from “Evolutionary history of the honey bee Apis mellifera inferred from mitochondrial DNA analysis”, published in Molecular Ecology also included the suggestion that the present subspecies divided less than one million years ago, as indicated by a 2% variation in the relevant mitochondria DNA.
The Middle East origin for honey bees was a surprising result. It went against prevailing notions, so other researchers were reluctant to accept the findings. However, in August of this year, confirming evidence was published. Using a larger sample set (140 honey bee genomes and 8.3 million SNPs) and more modern equipment, results were published in Nature Genetics in late August. Matthew Webster, researcher at the Department of Medical Biochemistry and Microbiology, Uppsala University (in Sweden) says, “The evolutionary tree we constructed from genome sequences does not support an origin in Africa.” Instead, our modern honey bee originated from common ancestors in the Near East and began a rapid dispersion about 300,000 years ago into Europe and Africa.
You may wonder if the study of the bees’ genetic tree has much relevance for today’s beekeeper. Here is something to note. Almost as a passing thought, researcher Matthew Webster adds, “In contrast to other domestic species, management of honeybees seems to have increased levels of genetic variation by mixing bees from different parts of the world. The findings may also indicate that high levels of inbreeding are not a major cause of global colony losses.” We can trust Webster on the factual part of this discovery – he is telling us that his world-wide samples of kept honey bees are more genetically diverse than other domestic species (i.e., pigs, sheep, goats, bananas, potatoes). It should then follow, he suggests, that Colony Collapse Disorder is not due to inbreeding of honey bees. Instead, it is more likely that some other factors are culpable in the disappearing disease that sporadically hits apiaries.