convergent evolution: a standalone construct

Charles Darwin's 1859 On the Origin of Species described how species from separate lineages can arrive at similar forms when they face similar demands, the pattern later named convergent evolution. E. Ray Lankester sharpened the vocabulary in 1870 by separating homology, a shared feature inherited from a common ancestor, from homoplasy, a resemblance that arose independently, and this homology versus homoplasy contrast still frames the concept today. Convergent evolution is the independent evolution of similar features in lineages that do not share those features through recent common ancestry, so that unrelated groups come to resemble one another in structure or function: the wings of birds and of bats, the streamlined body of sharks and of dolphins, and the camera eye of vertebrates and of octopuses are standard examples. The resulting similar features are called analogous, in contrast to homologous features that trace to a shared ancestor. What makes convergence a landmark of evolutionary biology is that it lets researchers separate similarity due to shared descent from similarity due to shared selective pressure, a distinction that underlies how evolutionary trees are reconstructed and how the limits and repeatability of adaptation are studied.[1][2][3]

Unit

A pattern of trait similarity between lineages, identified against their phylogeny rather than by common descent

Recovery means

Not applicable

Measured by

Inferred by mapping traits onto a phylogenetic tree and testing whether similar states arose independently, now quantified by dedicated convergence measures