Recurrent evolution

Recurrent evolution is the repeated evolution of a particular trait, character, or mutation. Most evolution is the result of drift, often interpreted as the random chance of some alleles being passed down to the next generation and others not. Recurrent evolution is said to occur when patterns emerge from this stochastic process when looking across multiple distinct populations. These patterns are of particular interest to evolutionary biologists, as they can demonstrate the underlying forces governing evolution.

Recurrent evolution is a broad term, but it is usually used to describe recurring regimes of selection within or across lineages.^[1] While most commonly used to describe recurring patterns of selection, it can also be used to describe recurring patterns of mutation; for example, transitions are more common than transversions.^[1] The concept encompasses both convergent evolution and parallel evolution; it can be used to describe the observation of similar repeating changes through directional selection as well as the observation of highly conserved phenotypes or genotypes across lineages through continuous purifying selection over large periods of evolutionary time.^[1]