Convergent evolution

Convergent evolution is the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy, from Greek for same form. The recurrent evolution of flight is a classic example of convergent evolution. Flying insects, birds, and bats have all evolved the capacity of flight independently. They have "converged" on this useful trait.

Functionally similar features arising through convergent evolution are termed analogous, in contrast to homologous structures or traits, which have a common origin, but not necessarily similar function. The British anatomist Richard Owen was the first scientist to recognise the fundamental difference between analogies and homologies. Bat and pterosaur wings constitute an example of analogous structures, while the bat wing is homologous to human and other mammal forearms, sharing an ancestral state despite serving different functions. The opposite of convergent evolution is divergent evolution, whereby related species evolve different traits. On a molecular level, this can happen due to random mutation unrelated to adaptive changes; see long branch attraction.