Leaf-Cutter Ants Select Fungus for Their Farms to Be More Productive with Time

It turns out that fungus-growing ants are picking when it comes to cultivating their crops. Scientists have discovered that a lineage of South American ants have an evolutionary history of improvement of their fungal crops.

Leaf-cutting ants harvest leaves from the surrounding forest. They then return to their nests where they use a broad range of fungal enzymes to degrade harvested leaf fragments. The fungus then produces clusters of inflated food packages for the ants, which the ants harvest in order to feed.

In this case, the researchers created a reconstruction of how fungus-growing ants have slowly improved their clonal crops into a robust and efficient farming system. More specifically, they showed that the delivery of some enzymes and vital amino acids in the fungal food explains why the ant farmers have lost the ability to produce these compounds themselves.

These food packages actually evolved about 20 million years ago. They represented an innovation that allowed today's leaf-cutting ants to evolve truly large-scale farms. About 50 million years ago, the ants actually became farmers, though the first 30 million years only had small-scale subsistence farms.

"Although it took ages of slow natural selection, today's ant farms are about 100,000 times larger than those of the first ancestors that invented farming," said Henrik De Fine Licht, one of the researchers, in a news release.

The findings reveal a bit more about how these ants evolved and created these farms

"It is as if the farming ant families and their underground gardens have become single organisms where queen, nurses, foragers, brood and fungus are connected in a huge interaction network," said De Fine Licht. "All parties make complementary contributions just like different tissues in a single body."

The findings are published in the journal Nature Communications.

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