The tiny, industrious ant has populated the world for millions of years. Humorously, their incredible success as a species can be attributed to their sheer number of individuals which have allowed them to overcome obstacles and make their homes in diverse locations. Despite their diminutive size, ants have managed to become one of the most successful species in the world.
Ants and flowering plants are known to have originated about 140 million years ago. They then became more prevalent and spread to new habitats. Were the evolutionary trajectories of the two groups related? How did ants populate the world?
The findings are published in the journal ‘Evolution Letters’. There are more than 14,000 different species. It is estimated that there are more than 4,000 billion individual ants on Earth. “They live on almost every continent, in different habitats. We are trying to understand how they could have diversified from a single common ancestor,” explains Matthew Nelsen. He is a research scientist at the Field Museum in Chicago (USA) and lead author of the paper.
Following the plants
About 60 million years ago, ants lived mainly in forests and built their nests underground. “Some plants evolved to exhale more water vapor through small holes in their leaves. The environment thus resembled a rainforest,” Nelsen explains.
In this wetter environment, some ants began to move their nests from the understory to the trees. Some of the flowering plants that lived in these forests began to spread outward. They thrived in drier conditions.
Nelsen’s work suggests that when the flowering plants left the forests, some ants followed them. It is possible that the plants provided them with an incentive in the form of food.
“Plants in these arid habitats evolved ways to feed the ants. Like elaiosomes, which are like fleshy appendages on the seeds,” notes Nelsen. And when the ants pick up the seeds to get the elaiosomes, they help disperse them.
Knowing how ants populated the world is vital to understanding current processes. Plants helped shape the evolution and dispersal of ants. It is especially important in light of the current climate and biodiversity crisis.
“This study demonstrates the important role of plants in shaping ecosystems,” says Nelsen in a statement. Changes in plant communities are affected by historical and modern climate change. They can cascade to animals and other organisms that depend on those plants.”