Trout evolution in a human lifetime.

Meta version Trout in Wyoming’s high country evolved new feeding anatomy in less than a human lifetime. A 2023 study in *Evolution*, led by Lucia Combrink at the University of Wyoming, looked at alpine lakes in the Wind River Range that were completely fishless until managers stocked them and wrote down the date. That gave researchers something rare: a natural experiment with a timestamp. They sampled trout from 2018 to 2021, sorted the lakes by stocking history, and compared fish from lakes stocked 47 to 89 years ago against recently stocked lakes and the original hatchery stocks. Then they measured gill rakers, the comb-like structures that filter food from water. More rakers, packed tighter, means a fish can capture smaller prey. The result: trout in the long-established lakes had significantly higher gill raker counts than both recently stocked fish and their hatchery ancestors. And the pattern showed up independently across multiple lakes and multiple species, which is exactly…