In a study published in Nature Genetics, researchers from Uppsala University present the first global analysis of genome variation in honey bees. The findings show a surprisingly high level of genetic diversity in honey bees, and indicate that the species most probably originates from Asia, and not from Africa as previously thought.
“The evolutionary tree we constructed from genome sequences does not support an origin in Africa,” said Matthew Webster, one of the authors. “This gives us new insight into how honey bees spread and became adapted to habitats across the world.”
Another unexpected result was that honey bees seem to be derived from an ancient lineage of cavity-nesting bees that arrived from Asia around 300,000 years ago and rapidly spread across Europe and Africa.
Extensive losses of honey bee colonies in recent years are a major cause for concern. Honey bees face threats from disease, climate change, and management practices. To combat these threats, it is important to understand the evolutionary history of honey bees and how they have adapted to different environments across the world.
“We have used state-of-the-art, high-throughput genomics to address these questions, and have identified high levels of genetic diversity in honey bees,” Webster said. “In contrast to other domestic species, management of honey bees 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.”
Also hidden in the patterns of genome variation are signals that indicate that climate change has strongly impacted honey bee populations historically.
“Populations in Europe appear to have contracted during ice ages, whereas African populations have expanded at those times, suggesting that environmental conditions there were more favorable,” said Webster.
The researchers also identified specific mutations in genes that are important in adaptation to factors such as climate and pathogens, including those involved in morphology, behavior, and innate immunity.
“The study provides new insights into evolution and genetic adaptation, and establishes a framework for investigating the biological mechanisms behind disease resistance and adaptation to climate — knowledge that could be vital for protecting honey bees in a rapidly changing world,” Webster said.
Read more at: