Brother Fruit Flies Forgo Fighting, Cooperate With Each Other When Searching For A Mate
This is a lesson for male fruit flies: if you need a wing man, it should be your brother. Researchers observed the benefits of such a choice — longer lifespans and more children — in a recent study, and the results were published in the journal Nature earlier this week.
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For the study, scientists at Oxford University's Department of Zoology presented female fruit flies with different groups of three male fruit flies. The first consisted of three brothers, fruit fly triplets. The second included two brothers and a third unrelated male. The third group was made up of three unrelated males. "As expected, within-group relatedness inhibits male competition and female harm," the researchers wrote.
The unrelated males brawled over the female. (According to The New York Times, fruit flies fight using their front legs.) The three brothers, on the other hand, didn't fight so much. Why? Three strangers feel pressure to ensure their genetic information is passed down to a new generation; brothers rest easy knowing the family line will continue. This behavior is known as kin selection.
But the cooperation among brothers has other benefits, which the three strangers tearing each other apart apparently haven't considered. First of all, the cooperation meant that all three brothers lived longer, and second, the female was able to reproduce more offspring for a longer period of time. Moreover, when fruit flies battle over a female, they tend to kill her in an all-or-nothing strategy.
"Because they have to compete so aggressively with each other, sometimes you can have paradoxical situations where there might be behaviors that enable a male to out-compete another male, but that also has negative side effects for the female," Tommaso Pizzari, an evolutionary biologist and lead author of the study, told the Los Angeles Times. When a female was exposed to related males, she lived longer, had greater reproductive success, and was capable of reproducing later in life.
The benefits of brotherly love were obvious. But when the female was presented with two brothers and one stranger, something strange happened. "We don't fully understand what is happening," Pizzari says. The stranger, it turns out, was able to infiltrate the brothers' cooperation and reproduce with the female fruit fly far more frequently than the brothers. "The unrelated male sired on average twice as many offspring as either brother," they wrote in the study. Another thing the researchers don't really understand is how the male fruit flies differentiate kin from stranger, the LA Times reported. The leading theory is that they sense it through pheromones.
Above photo courtesy of Shutterstock
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