Convergent evolution
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In cultural evolution, convergent evolution is the development of similar cultural adaptations to similar environmental conditions by different peoples with different ancestral cultures.
An example of convergent evolution is the similar nature of the flight/wings of insects, birds, pterosaurs, and bats. All four serve the same function and are similar in structure, but each evolved independently. Some aspects of the lens of eyes also evolved independently in various animals.
Convergent evolution is similar to, but distinguishable from, the phenomena of evolutionary relay and parallel evolution. Evolutionary relay refers to independent species acquiring similar characteristics through their evolution in similar ecosystems, but not at the same time (e.g. 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
- Spines have evolved in several mammal groups independently - Echidnas (Monotremes), Hedgehogs (insectivores), Old World porcupines (Rodents) and New World porcupines (a separate group of rodents). In this case, because the two groups of Porcupines are relatively closely related, they would be considered to be an example of parallel evolution; neither Echidnas nor Hedgehogs, however, are closely related to Rodents at all. In fact the last common ancestor of all four groups was a contemporary of the Dinosaurs.
- Cat-like, sabre-toothed predators evolved in three distinct lineages of mammals — Sabre-toothed cats, Nimravids (false sabre-tooths), and the marsupial thylacosmilids.
- The monotreme Platypus is remarkably similar in appearance and lifestyle to semi-aquatic placental mammals such as the beaver.
- The Little Auk of the north Atlantic (Charadriiformes) and the diving petrels of the southern oceans (Procellariiformes) are remarkably similar in appearance and habits.
- The similar evolution of auks in the Northern Hemisphere and penguins in the Southern Hemisphere.
- vultures come in two varieties as a result of convergent evolution: the Old World vultures are in the eagle and hawk family and use eyesight for food discovery; the New World vultures are related to storks and use the sense of smell (as well as sight) to hunt. Both kinds of vulture eat carrion and typically have featherless necks. In both cases they search for food by soaring, circle over carrion, and group in trees.
- the Flightless Cormorant of the Galapagos Islands, unlike other cormorants, now has non-flight wings, equal in proportion to the swimming penguins. It feeds in proximity to the shoreline.
- Honeyeaters of Oceania, Flowerpeckers of Australasia, and Sunbirds of Africa evolved separately although all feed on nectar.
- 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 Neotropical poison dart frog and the Mantella of Madagascar have independently developed similar mechanisms for obtaining alkaloids from a diet of ants and storing the toxic chemicals in skin glands. They have also independently evolved similar bright skin colors that warn predators of their toxicity.
- Assassin spiders are a group comprised of two genetic lines which apparently evolved separately. They have very long necks, fangs larger in proportion than any other spider, and hunt other spiders by snagging them from a distance.
- 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 existence of distinct families of carbonic anhydrase is believed to illustrate convergent evolution.
- Bats are classified into two distinct morphological groups: the megabats (Megachiroptera) and the microbats (Microchiroptera). Some studies in the 1990s suggested that these two groups evolved completely separately and that the megabats may be related to primates, particularly flying lemurs. More recent molecular and morphological evidence (reviewed in [link]), however, provides strong support for the monophyly of all living bat species.
- Koalas of Australasia have evolved fingerprints, very similar to those of humans.
See also
| Topics in evolutionary ecology
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| Patterns of evolution: Convergent evolution | Evolutionary relay | Parallel evolution |
| Colour and shape: Aposematism | Mimicry | Crypsis |
| Interactions between species: Mutualism | Cooperation | Predation | Parasitism |
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