Fungus-farming ants are dependent on cultivating fungus gardens for food, and it has been widely believed the fungi also evolved dependence on the ants for their dispersal and reproduction. When young ant queens establish new colonies, they take a start-up crop of fungi with them from their parental garden.
Graduate student Alexander Mikheyev and Dr. Ulrich Mueller, professor of integrative biology, have now found that the fungi reproduce sexually and disperse widely without the aid of their ant farmers.
Different genera of the ants, it turns out, are essentially cultivating the same fungus across wide geographical areas.
The scientists' finding provides a new perspective on coevolutionary processes. Coevolution, like that between honeybees and the flowers they pollinate, occurs when two or more species influence each other's evolution over time. Mikheyev says that two species don't necessary need to have a very specific, one-to-one relationship in order to coevolve.
"This shows that coevolution can proceed without specificity at the species level," said Mikheyev. "It has been believed that mutualistic interactions, as well as parasitic ones, are very specific and one-to-one. We are beginning to realize that this is not necessary for long-term coevolutionary stability, with the leaf-cutting ants being a dramatic example."
The research was published June 26 in Proceedings of the National Academy of Sciences.
"Previously, the fungi were thought to be passive players, moved around by the ants," said Mikheyev. "We show that the power of fungal dispersal is probably beyond ant control."