Scientists call the phenomenon “evolutionary rescue” — when a species’ genetic diversity allows it to survive amid extreme threats.

Wild scarlet monkeyflowers in California survived a historic drought by relying on a rapid evolution, marking the first time the process has been observed in the wild.

A potted scarlet monkeyflower would die within a few days without water. But multiple natural populations of the species survived an extreme, four-year drought in California, and researchers now know ...