Ants are the most species-rich family among social insects, with more than 15,000 species worldwide. They originated around 140 to 168 million years ago but didn’t rise to ecological dominance until 66 million years ago, when an asteroid ended the age of dinosaurs. Scientists now know exactly what allowed ants to triumph after this mass extinction.
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The research was conducted by an international team of scientists led by Lukas Schrader from the Institute for Evolution and Biodiversity at the University of Munster, Germany. The findings are published in the journal Science Advances.
By analysing and comparing the genomes of 163 ant species from 12 of the 16 ant subfamilies living today, the researchers were able to reconstruct the evolutionary history of these animals over the past 100 million years.
The analysis revealed that ants benefited from so-called transposable elements in their DNA, often referred to as ‘jumping genes’. These are DNA sequences that can move and replicate within a genome. For a long time, science regarded them as ‘genomic parasites’ – similar to viruses, they were thought to multiply in the genome without benefiting the host and, in the worst case, cause diseases.
Now, ‘jumping genes’ are increasingly being recognised as engines of evolutionary innovation. According to the new study, those ant lineages carrying the most transposable elements in their genomes are also the most species-rich today.
The researchers were able to identify independent bursts of transposable element activity in the ancestors of the largest ant groups in the early Palaeogene (about 66 million years ago), shortly before these lineages diversified into the thousands of species we know today.
“The asteroid impact had dramatic consequences for the environment. We have now found the genomic mechanism that connects these ecological upheavals to the subsequent rapid diversification of the ants: transposable elements,” said Schrader.
Similar patterns have been identified in other animal groups, with studies showing bursts of jumping gene activity during phases of increased speciation, for example in bats.
The new study also linked jumping genes to the expansion of gene families involved in chemical communication, which is essential to the social life of ants – they navigate, recognise nestmates and coordinate colonies almost exclusively by smell.
Scientists think this ability to recognise and interpret chemical signals may have been enhanced by the activity of their genomes.
Read the full findings here.
Top image: a group of red ants. Credit: Nuoriginal2017/Getty Images
