This is how ants conquered the world

by time news

In the countryside, in any garden or urban park, in the cracks in the concrete and often even inside the house… Ants are literally everywhere. Except in Antarctica, where their presence has not yet been detected, there are more than 14,000 known species of ants spread throughout the world. Researchers estimate that there are more than four trillion individual ants on Earth, and that their combined biomass is similar to that of humans, despite the fact that each ant weighs about 35 million times less than a person…

However, despite their abundance, the ants keep a secret: no one had managed to find out how they evolved to spread throughout the planet. Now, in a new study just published in the journal ‘Evolution Letters’, a group of scientists claim to have found the answer.

Using a combination of fossils, DNA, and data on the habitat preferences of modern species, researchers have managed to piece together how ants and plants have evolved together over the past 60 million years. In fact, they found that when flowering plants spread out of forests, ants followed, kick-starting the evolution of the thousands of species living today.

“When you look around you,” explains Matthew Nelsen, lead author of the study, “you can see ants on almost every continent, occupying a multitude of different habitats, and even different sizes of those habitats: some ants live underground, others live in the treetops. We are trying to understand how they were able to diversify from a single common ancestor to occupy all these spaces.”

140 million years of history

Scientists have long known that both ants and flowering plants (called angiosperms) arose around 140 million years ago and spread rapidly across a wide variety of habitats. But Nelsen and his colleagues wanted something more: to find evidence that the evolutionary mechanisms of the two groups were closely connected.

To find that link, the researchers compared the climates in which 1,400 modern ant species live today, including data on temperature and rainfall. They then combined this information with a time-scale reconstruction of the ant family tree, based on genetic information and fossils preserved in amber. Many ant behaviors, such as where they build their nests and what habitats they live in, appear to be deeply embedded in the lineages of their species, to the point that scientists can make pretty good guesses about the lives of prehistoric ants based on their behaviors. modern relatives. By combining that data with similar information about plants, the world of the first ants was laid bare.

a shared history

About 60 million years ago, ants lived mainly in forests and built their nests underground. “But around this time,” says Nelsen, “some of the plants in these forests evolved to breathe out more water vapor through little holes in their leaves; They made the whole place much wetter, so the environment became more like a tropical rain forest.” In this environment, some of the ants began to move their nests from underground to the trees. And they were not the only ones, since animals such as frogs and snakes, along with other plants, also moved to the trees at the same time, helping to create new tree communities.

Afterwards, some of the flowering plants that lived in these forests began to ‘migrate’, spreading outwards, inching towards more arid regions and adapting along the way to thrive in drier conditions. The work of Nelsen and his team suggests that, at the same time, some of the ants followed them.

The plants could have provided an incentive for the ants in the form of food. “Other scientists -Says Nelsen- have shown that plants in these arid habitats were developing ways to ‘make’ food especially for the ants, including things like eleosomes, which are like fleshy appendages on seeds.” Something very useful for plants, since when the ants take the seeds to obtain the eleosomes, they help to disperse them.

In their paper, the researchers say that showing how plants helped shape the evolution and spread of ants is especially important in light of the climate and biodiversity crises we are facing today.

“This study -concludes Nelsen- shows the important role that plants play in shaping ecosystems. Changes in plant communities, such as those we see as a consequence of historical and modern climate change, can affect the animals and other organisms that depend on these plants.”

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