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article imageMass extinction event wiped out bees as well as dinosaurs

By Robert Myles     Oct 27, 2013 in Science
Manchester - Fossil records show dinosaurs suffered mass extinction about 65 million years ago. Scientists have long suspected bees underwent a similar fate but they’ve only now documented a mass extinction event affecting bees.
According to new research, a wipe-out of prehistoric pollinators occurred contemporaneously with dinosaurs disappearing. The new study focused on carpenter bees, or Xylocopinae, to give the bee group its Latin name.
Lead author, Sandra Rehan, an assistant professor of biological sciences at the University of New Hampshire (UNH) along with colleagues Michael Schwarz of Australia’s Flinders University and Remko Leys at the South Australia Museum, modeled a mass die-off affecting this bee species at a particular point in time between the Cretaceous and Paleogene Eras, called the K-T boundary.
Their research could help explain sharp declines seen in bee species worldwide over recent years.
Previous research pointed to flowering plants undergoing widespread die back at the K-T boundary, with a knock-on effect on the bees, a species dependent on such plants. The problem was that unlike massive dinosaurs, whose fossil records survived in some cases miraculously intact, bee fossil records are relatively poor making deduction of a mass extinction affecting these insects difficult.
Rehan and colleagues overcame the lack of bees’ fossil records in a novel way. They analyzed live specimens of contemporary carpenter bees gathered from every continent except Antarctica.
Using a technique known as molecular phylogenetics, the researchers analyzed the DNA sequences of four “tribes” from 230 species of carpenter bees to examine their evolutionary relationships. In so doing, patterns began to emerge consistent with a mass extinction having affected the bees. By combining such fossil records as existed with DNA analysis, the scientists introduced time into their calculations, learning not just how the bees were related, but how old were the different “tribes” of carpenter bees.
Commenting on the results, Rehan said, “The data told us something major was happening in four different groups of bees at the same time and it happened to be the same time as the dinosaurs went extinct.”
Rehan added, “If you could tell their whole story, maybe people would care more about protecting them. Understanding extinctions and the effects of declines in the past can help us understand the pollinator decline and the global crisis in pollinators today.”
The UNH study has implications in the search for an explanation of the current widespread decline in bee populations. Many plants won’t grow without pollination from bees. In the United States alone, it’s estimated that $15 billion worth of crops would vanish without bees. Quite apart from the cost, the effect on diet would be considerable as demonstrated by the list of everyday foodstuffs pollinated by bees. Biodiversity of plant species would also take a hit with as yet unknown knock down effects for other insects and plants.
Variations in the method of collecting statistics for measuring what has become known as Colony Collapse Disorder, affecting bee populations in North America and Europe, have made precise measurement of the decline in bee populations difficult, but the anecdotal evidence consistently points to bees dying off at an alarming rate on both sides of the Atlantic.
The UNH article — “First evidence for a massive extinction event affecting bees close to the K-T boundary” — was published in the Oct. 23, 2013 edition of PLOS ONE.
More about Bees, Honey bees, mass extinction, Mass extinctions, Cretaciousteriary mass extinction
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