The Red King hypothesis is a relatively new idea in evolutionary biology. It suggests that two organisms from two different species, those that work together in some way, will have slow rates of evolution in order to stop the other becoming too “selfish” and getting all the benefits that a faster evolving organism would bring to the table.
However, a new study in Nature Communications on ants and plants in Central America finds that this may not always be the case. For their study, a team of researchers analyzed the genomes of ants evolved to protect the Acacia plant, which provides them with both food and shelter. These ants are incredibly aggressive and attack anything they deem to be even a possible threat to the plants in their day-to-day lives.
They then compared their pace of evolution with those of other ants that live in the same location in Costa Rica – these ordinary ants are far more passive, fleeing predators and aggressors when their own nests are at risk. The Red King hypothesis would suggest the ants would have a slow rate of evolution in order to keep up with the plants’ presumed slow rate, but they found that the opposite was true – these mutualistic ants had a very high rate of evolution.
Although it’s not yet clear why this has happened, Corrie Moreau, a professor at the Field Museum in Chicago and a co-author of the study, told The Independent that the plants and ants are trying to keep up with each other and not fall behind. In this case, the Red King may have been overthrown by the Red Queen hypothesis, another evolutionary effect that’s been known about long before the King entered the stage.
A Pseudomyrmex ant, the type that protects the acacia plant in Central America. Credit: antweb.com/Wikimedia Commons; CC BY-SA 3.0