Convergent evolution
From Freepedia
In evolutionary biology, convergent evolution describes the process whereby organisms not closely related independently acquire similar characteristics while evolving in separate and sometimes varying ecosystems.
An example of convergent evolution is the similar nature of the wings of insects, birds, and bats. All three serve the same function and are similar in structure, but each evolved independently. Eyes also evolved independently in various animals.
Convergent evolution is a different phenomenon than evolutionary relay and parallel evolution. Similar to convergent evolution, evolutionary relay describes how independent species acquire similar characteristics through their evolution in similar ecosystems, but not at the same time (dorsal fins of extinct ichthyosaurs and sharks). Parallel evolution occurs when two independent species evolve together at the same time in the same ecospace and acquire similar characteristics (extinct browsing-horses and extinct paleotheres).
Structures that are the result of convergent evolution are called analogous structures or homoplasies; they should be contrasted with homologous structures which have a common origin.
Other examples
- The smelling organs of the terrestrial coconut crab are similar to those of insects.
- The aerial rootlets found in English ivy (Hedera helix) are similar to those of the wintercreeper (Euonymus fortunei) (and other vines). These rootlets are not derived from a common ancestor, but have the same function of clinging to whatever support was available.
- The Neotropical poison dart frog and the Mantella of Madagascar have independently developed similar mechanisms for obtaining alkaloids from a diet of ants, and for storing the toxic chemicals in skin glands. They have also independently evolved similar bright skin colors that warn predators of their toxicity.
- The similarities in diet and activity patterns between the thorny devil (Moloch horridus) and the Texas horned lizard (Phrynosoma cornutum) both in different clades.
- The Marsupial Thylacine and the Placental Wolf.
- The Little Auk of the north Atlantic (Charadriiformes) and the diving petrels of the southern oceans (Procellariiformes) are remarkably similar in appearance and habits.
- Cat-like, sabre-toothed predators evolved in three distinct lineages of mammals — Sabre-toothed cats, Nimravids (false sabre-tooths), and the marsupial thylacosmilids.
- The existence of distinct families of carbonic anhydrase are believed to illustrate convergent evolution.
