The ritualized fighting behavior of one ant species is linked to increases in dopamine levels that trigger dramatic physical changes in the ants without affecting their DNA, according to research from North Carolina State University, Arizona State University and the U.S. Department of Agriculture.
The researchers studied Indian jumping ants (Harpegnathos saltator), which can undergo significant changes in physiology without any related changes to their DNA. Instead, the changes depend on which genes are turned on or off which in turn is determined by social and environmental factors. This has made them a model organism for epigenetics researchers.
When an H. saltator colony's queen dies, the female workers engage in ritual fights to establish dominance. While these battles can be fierce, they rarely result in physical injury to the workers. Ultimately, a group of approximately 12 workers will establish dominance and become a cadre of worker queens or "gamergates." Video of the ritualized fighting behavior can be seen at https://www.youtube.com/watch?v=74ruqyOUX-8.
The gamergates look like ordinary workers, but undergo extreme internal changes: their brains shrink by 25 percent; their ovaries expand to fill their abdomens; and their life expectancy jumps from about six months to several years or more.
"We wanted to know what's responsible for these physical changes," says Dr. Clint Penick, lead author of a paper describing the work and a postdoctoral researcher at NC State. "The answer appears to be dopamine. We found that gamergates have dopamine levels two to three times higher than other workers."
To understand what was happening, the researchers took a subset of workers from a colony (Colony A) and separated them from their gamergates. These workers effectively formed their own colony (Colony B) and began fighting to estab
|Contact: Matt Shipman|
North Carolina State University