Observing wild population of guppies in the rainforest of Trinidad, the researchers found that female guppies swim in habitats that contain few males � but many predators. "Male guppies spend most of their time displaying to females. But if their courtship displays don't impress the females, males will attempt to sneak mating with them when they aren't looking," says Croft.

Male guppies are brightly colored to attract female attention, while female guppies are a dull brown color. The researchers show that female guppies might use this color difference to their advantage, venturing into the deep water where predators lurk. The males' bright coloring also attracts predators, making it too dangerous for them to follow.

"Understanding why and how [sexual segregation] occurs is essential if we are going to conserve and protect species and habitats," explains Croft, who points out that fish are not the only species who display this social characteristic. "In many ecosystems, predators are the first to go extinct, and our work shows that this may have many, perhaps unexpected, effects. In this case, females may suffer more sexual harassment."

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