The evolutionary process in which unrelated species develop similar traits in similar environments is convergent evolution.
Convergence occurs when natural selection repeatedly produces comparable solutions to similar environmental challenges. The species involved may be distantly related, so their shared feature was not inherited from a recent common ancestor. The resulting similarities are often called analogous traits.
Flight is a classic example. Insects, birds, pterosaurs, and bats evolved the ability to fly independently, using different anatomical structures. Echolocation also evolved separately in bats and toothed whales. Their similar abilities reflect comparable pressures and physical constraints, not close evolutionary kinship.
Convergent evolution is often confused with parallel or divergent evolution. Divergent evolution occurs when related organisms become increasingly different as they adapt to different conditions. Parallel evolution describes similar changes in separate lineages whose ancestors may have shared more traits, although the boundary between parallel and convergent evolution is not always sharp. Coevolution is different again: it describes reciprocal evolutionary change between interacting species, such as predators and prey or flowers and pollinators.