1292. Fruit Fly Brothers Tend to Cooperate

By Sindya N. Bhanoo, The New York Times, January 24, 2014

A fruit fly. Zach Wise for The New York Times

In pursuit of a mate, male fruit flies often engage in combat, battling one another with their front legs.

But when the flies are brothers, they are more likely to cooperate, researchers are reporting. In a new study in the journal Nature, Tommaso Pizzari, a zoologist at the University of Oxford, and colleagues write that brother flies live longer as a result.

And there are clear benefits for females who live among brothers: They have a longer reproductive life span, a faster rate of egg production and a greater chance of laying eggs that mature to adulthood.

The researchers exposed female flies in a laboratory to several different sets of males — three brothers; two brothers and an unrelated male; and three unrelated males.

The most peaceful groups were the ones with three brothers, perhaps because supporting one’s kin is an alternative way to pass on common genes.

“You can improve your reproductive success yourself or help individuals who also share your genes,” Dr. Pizzari said.

Although fruit flies have been extensively studied in labs, the structure of their natural societies remain a bit of a mystery.

Still, Dr. Pizzari suspects that in nature, brothers are supporting brothers to some degree. “Sex implicitly brings potential for conflict,” he said, “but population structure can modulate how much conflict there is.”