Plants have been using ants to spread seeds and sometimes act as bodyguards against predators, a new study suggests.
While plants have been providing ants with nectar to eat, researchers found that plants have also evolved to take advantage of its relationship with ants.
How Plants Are Using Ants
In the study published in the journal Proceedings of the National Academy of Sciences, researchers looked at the genetic history of about 1,700 species of ants and 10,000 genera of plants. The goal was to find out how the relationship between plants and ants came to be, and how it has affected their respective evolutionary histories.
Plants have certain characteristics that purposely attract the ants. Some plants have hollow thorns for ants to live inside and excess nectar to bribe them into staying. While ants can just run off with the nectar, some will stay, and attack anything that poses as a threat to the plant.
Some plants, meanwhile, trick ants into spreading seeds by attaching them into food packets. The ants will then move away, eat the food packet, and discard the seeds called elaiosomes in an area where it will grow better.
Plants And Ants Evolving Together
The question, however, was how exactly this give-and-take relationship between plants and ants have started.
"It was a chicken-and-egg question, whether things started with ants developing behaviors to take advantage of plants, or plants evolving structures to take advantage of ants," said Rick Ree, co-author of the study and a curator at the Field Museum.
To trace back how this relationship started, the researchers analyzed DNA and ecological data of plants and ants. They linked the behavioral characteristics and physical features to the family trees of both ants and plants to study when plants began giving ants food and when ants started helping out plants.
The researchers found that ants have long been relying on plants before plants figured out they can use ants to spread seeds and as a defense against predators. Plants did not evolve certain characteristics, such as specialized structures, until long after ants have depended on plants for food and habitat.
In an evolutionary standpoint, however, the study added that species of ants nesting in plants do not seem better off than those that do not. Matt Nelsen, also an author of the study, added that these ants to do not grow faster nor diversify because of the interaction.