Guppies Sacrifice Looks When Predators are Around

Trinidadian guppies (Poecilia reticulata). Image courtesy of voylodyon/Shutterstock Male guppies develop flashy colors to woo potential mates. Their colorful displays grab the attention of the ladies, but also the predators. With sexual selection telling the males to stand out and natural selection encouraging them to blend in, what's a guppy to do? While coloration is coded in the male fish's genes, the expression fluctuates. Environmental factors such as food and predators push the fish to be more or less colorful. Researchers wanted to know just how much wiggle room the genes allowed in coloration, a concept called "phenotypic plasticity," so they put the guppies to the test. The researchers raised four groups of male Trinidadian guppies (genetic brothers) and exposed each to a different environment: one with plenty of color-inducing food, and another with only half as much; one with chemical signals in the water from a common predator called ...