TALLAHASSEE, Fla.--In the natural stream communities of Trinidad, guppy populations live close together, but evolve differently. Upstream, fewer predators mean more guppies but less food for each; ...

This is your first of three free stories this month. Become a free or sustaining member to read unlimited articles, webinars and ebooks. Guppies are great at gobbling up mosquito larvae, and humans ...

Guppies make unassuming pets, but in the wild they adopt a daring and counterintuitive tactic to avoid becoming dinner. When they spot a predator, they suddenly darken their eyes from silver to jet ...