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Wednesday, September 1, 2010

For wasps, honesty is the best policy

Many animals that face off against rivals for mates or resources use specific clues to indicate their fitness levels. This allows weaker individuals to retreat without injury. But what happens when an inferior specimen counterfeits physical superiority signals? Elizabeth Tibbetts and Amanda Izzo of the University of Michigan found that, in the case of paper wasps, that deception comes with a price.

Female paper wasps of the species Polistes dominulus aggressively compete to become ruler of each colony. To save time and energy, they use facial patterns as fitness clues, with more fragmented patterns belonging to stronger females. Tibbetts and Izzo altered one group of wasps’ facial patterns to make them appear either stronger or weaker than they actually were. They treated a second group of wasps with hormones to make them act more aggressively. A final group was treated so that they both looked and acted strong.

This is a portrait of nine Polistes dominulus paper wasps, illustrating the variation in facial patterns that functions as a signal of fighting ability

Credit: Elizabeth Tibbetts

Wasps whose appearance did not match their behavior were treated harshly by their unaltered peers. Wasps who looked strong but were actually weak suffered from aggressive treatment by other wasps. The wasps who looked weak but were actually strong were not physically punished, but were unable to get their fellow wasps to submit to them. Thus, their superior strength was socially useless to them.

The one group of altered wasps that did not suffer were the ones that were both physically and hormonally altered. Their aggression levels and strength matched their appearance, and they were rewarded for their honesty.