What term describes the process of unrelated species evolving similar traits due to similar environments?

The process in which unrelated species evolve similar traits because they face similar environments is called convergent evolution. These similarities arise independently rather than being inherited from a recent common ancestor.

A classic example is flight. Insects, birds, pterosaurs, and bats each evolved the ability to fly in separate lineages, producing functionally similar wings through different evolutionary histories. Sharks and dolphins also provide a familiar example: their streamlined bodies suit fast swimming, even though sharks are fish and dolphins are mammals.

Traits produced by convergence are often called analogous structures when they have similar functions but different evolutionary origins. This contrasts with homologous structures, such as the forelimbs of humans, bats, and whales, which reflect shared ancestry even when their functions differ. Convergent evolution is encouraged when organisms encounter similar ecological pressures or physical constraints. It is related to parallel evolution, but the terms are not identical: parallel evolution usually refers to related lineages independently evolving similar changes, while convergence often emphasizes more distantly related organisms.