Invasive Asian honeybees have defied evolutionary expectations and established a thriving population in North Queensland during the past decade, much to the chagrin of the honey industry and biosecurity officials.
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The species, Apis cerana, is said to have overcome what is known as a genetic bottleneck to grow from a single swarm into a population of more than 10,000 colonies across a 10,000 square kilometre area.
Co-lead author Dr Rosalyn Gloag from the University of Sydney School of Life and Environmental Sciences said the research published in Current Biology showed that some species could quickly adjust to new environments despite starting with very low genetic diversity relative to their native-range populations.
Dr Gloag said that high genetic diversity was generally assumed to be important for a population to quickly adapt to changing environmental conditions, such as when a species was translocated or experienced rapid environmental change caused by natural or climate change disasters.
"However, we have shown that this invasive population of honeybees has rapidly adapted since its arrival, despite having suffered a steep loss in genetic diversity," she said.
Dr Gloag said the research was particularly important because of anthropogenic climate change.
Studying the invasive population in Queensland gave the research team a rare complete genetic timeline of a natural invasion, beginning from soon after the bees arrived.
The invasive bees are thought to have come from Papua New Guinea in 2007.
Despite initial concerns, the bees were found not to be carrying the most feared of its parasites, the varroa mite, which subsequently arrived in Australia by an unknown route, threatening the domestic honey industry.
"We were lucky to have a complete sample timeline of this invasive population thanks to the incredible efforts of the Queensland Department of Agriculture and Fisheries, which sampled the population extensively during the early years of the incursion as part of an eradication attempt," Dr Gloag said.
"Although that attempt was unsuccessful, the biological material collected has been incredibly valuable for understanding how these invasions proceed. And that in turn helps us prepare better for future invasions," she said.
Access to this comprehensive sample set allowed the scientists to re-sequence entire genomes of 118 individual bees collected over 10 years.
"We could essentially observe natural selection acting over time in a population that started with low genetic diversity," Dr Gloag said.
"From this unique vantage point, we could see that selection was acting on the variation in genomes that had arrived with the handful of original bees. It wasn't variation that arose later by mutations.
"In other words, some species with very low genetic diversity can adapt very quickly," she said.
"While this might be bad news for environments coping with newly arrived invasive species, it's potentially good news for populations that have temporary crashes in the face of climate change or other natural or human-induced disasters, such as bushfires."
Scientists from York University, Canada; IPB University, Indonesia; Bandung Institute of Technology, Indonesia; and the CSIRO, Australia; collaborated on the project.
