The concept of zombie ants might seem difficult to understand, but the way that these creatures adapted to climate change has some scientists wanting more insight.
Background Of Zombie Ants
A "zombie ant" is a nickname for when a dead ant gets infected by a parasitic fungus called Ophiocordyceps. The fungus takes over the body of the ant and controls its normal movements.
After the fungus takes over the ant's body, it commands the ant to bite or clamp onto a leaf and hang upside for several months. During this time, the fungus grows out so that it can infect future victims below.
What Was Discovered About Zombie Ants?
A new study, published on May 28 in the journal Evolution, revealed that zombie ants bite into different parts of the leaves because the fungus has adapted to climate change. The location on the leaf of the actual bite depends largely on local climate conditions.
"In tropical areas, zombie ants bite onto leaves, but in temperate areas, they bite twigs or bark," said study co-author professor David P. Hughes.
The researchers believe that the zombie ants adapted to these changes between 20 and 40 million years ago.
In the study, researchers described how ants clamped down on twigs in temperate climates because the leaves would eventually fall off them. But in warm climates, such as the Amazon, they clamped onto the leaves.
"In the late summer and early fall there are both leaves and twigs everywhere the ants reside," said study co-author and postdoctoral scholar Raquel G. Loreto. "But in temperate areas, the trees are deciduous and lose their leaves in the fall. There, the ants bite onto twigs."
Researchers believe that this was likely an evolutionary trait. The zombie ants that adapted to changing climates and bit different parts of the leaves survived. The zombie ants that did not adapt to climate changes would then die.
How Was It Discovered?
To reach this conclusion, researchers studied samples of zombie ants in museums and other collections. They also examined DNA samples from different types of fungi.
Researchers noticed a trend between the zombie ants. The ones that existed in warmer climates clamped onto the leaves, and the temperate zombie ants always went for the twigs and bark. The scientists hypothesized that the leaf biting was the original ancestral trait before climate change emerged.
Although zombie ants are not found in Europe, the researchers located a 47 million-year-old fossil from Germany that showed leaf biting.
"We suspect that it was also present in North America, and as those populations responded to climate change and the cooling temperature, we see a shift from biting leaves to dying on twigs," said Hughes.
