Ants evolved far earlier than previously believed, as far back as 140 million to 168 million years ago — and they have plants to thank for their diversity, U.S. researchers reported Thursday.
Researchers at Harvard University used a genetic clock to reconstruct the history of ants, and found that the ant family first arose more than 40 million years earlier than previously thought. The family did not diversify into different genera and species until flowering plants came onto the scene, they said.
The study sheds light on one of the most important and numerous animals, which includes hundreds of different species.
"We estimate that ant diversification took off approximately 100 million years ago, along with the rise of flowering plants, the angiosperms," Naomi Pierce, a professor of biology who led the study, said in a statement.
"These plants provided ants with new habitats both in the forest canopy and in the more complex leaf litter on the forest floor, and the herbivorous insects that evolved alongside flowering plants provided food for ants."
Writing in Friday's issue of the journal Science, the researchers said they reconstructed the ant family tree using DNA sequencing of six genes from 139 ant genera, encompassing 19 of 20 ant subfamilies around the world.
Such "molecular clocks" are widely used, alongside fossil and other evidence, to determine how old species are. They work on the basis that DNA mutates at a steady and calculable rate.
"Ants are a dominant feature of nearly all terrestrial ecosystems, and yet we know surprisingly little about their evolutionary history: the major groupings of ants, how they are related to each other, and when and how they arose," said graduate student Corrie Moreau.