About 66 million years ago, an asteroid struck Earth and brought the age of the dinosaurs to an end. The mass extinction that followed opened ecological opportunities for many other animals, including ants. New research suggests that mobile stretches of DNA known as transposable elements, or “jumping genes,” may have helped ants diversify and become the world’s most species-rich family of social insects.
How “jumping genes” may have driven ant diversification
More than 15,000 ant species have been identified worldwide. In a study published in Science Advances, an international research team reports that the insects’ evolutionary success was partly associated with transposable elements—segments of DNA that can move to new locations in the genome and make additional copies of themselves.
The study was led by Dr. Lukas Schröder of the Institute for Evolution and Biodiversity at the University of Münster in Germany.
Scientists once regarded transposable elements largely as “genomic parasites” because, like viruses, they can reproduce without providing an obvious benefit to their host. Their activity can sometimes disrupt genes and contribute to disease. More recently, however, researchers have recognized that these mobile elements can also create opportunities for evolutionary change.
When the researchers compared different ant groups, they found that lineages with more transposable elements generally had more species alive today.
The timing of the genetic activity was also significant. Several major ant lineages experienced distinct surges in transposable-element activity during the early Paleogene period, beginning about 66 million years ago. These bursts occurred shortly before ants expanded into the thousands of species found today.
“The asteroid impact had a dramatic impact on the environment. We have now discovered a genomic mechanism – a transposable element – that links these ecological upheavals to the subsequent rapid diversification of ants,” explains Lucas Schröder.
Ants are not the only animals to show this pattern. Previous studies have linked periods of increased transposable-element activity with the emergence of new species in groups including primates and bats.
Genetic changes linked to ant communication
The researchers also identified an association between transposable elements and the expansion of gene families involved in chemical communication.
Of particular importance were genes that encode odor receptors. These receptors allow ants to detect and respond to chemical signals and are essential to almost every aspect of their social behavior. Ants depend heavily on chemical cues to navigate their surroundings, recognize colony members and coordinate activities.
The findings suggest that transposable elements may have helped expand these sensory systems, improving ants’ ability to detect and interpret the chemical messages that support their complex societies.
Tracing ant evolution across 100 million years
To examine how transposable elements influenced ant evolution, the international team analyzed and compared the genomes of 163 ant species. The species represented 12 of the 16 surviving ant subfamilies, providing broad coverage of the genetic diversity found among modern ants.
Using these comparisons, the scientists reconstructed how transposable elements evolved and changed their activity over the past 100 million years.
The results reveal a strong association between ancient bursts of transposable-element activity and later diversification in ants. The findings suggest that DNA sequences once dismissed as genetic parasites may have helped one of Earth’s most successful insect groups evolve and thrive.
Source: www.sciencedaily.com