Ants that conquered the world

In a first, Japanese researchers have compared gene sequences from 300 species of Pheidole - world's most species-rich ant genus. It suggests that Pheidole evolved the same way twice, once to take over the New World and then again to take over the Old World.

The team from Okinawa Institute of Science and Technology Graduate University used gene sequences to construct a tree that shows when and where each species evolved into new species.

At the same time, in a parallel effort, they scoured the academic literature, museums around the world, and large databases to aggregate data on where all 1,200 or so Pheidole species live on Earth, creating a range map for each species.

"If you go into any tropical forest and take a stroll, you will step on one of these ants," said professor Evan Economo.

The new world and the old world are almost completely independent of each other.

"Pheidole first evolved in the new world, from one species to over 600 species. Then, one of those ants colonised the old world where it evolved into another 600 or so ant species," added Economo.

Till now, researchers have never had a global perspective of how the many species of Pheidole evolved and spread across the Earth.

The new work will help scientists get a better handle on these organisms that are dominant features of many of Earth's ecosystems.

The results were published in the journal Proceedings of the Royal Society Series B.