Adaptive radiation
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Image:Darwin's large finches.jpeg
Adaptive radiation describes the rapid speciation of a single or a few species to fill many ecological niches. This is an evolutionary process driven by mutation (heritable/genetic variation) and natural selection.
There are three basic types of adaptive radiation:
- General adaptation. A species that develops a radical new ability can reach new parts of its environment. An example of general adaptation is bird flight.
- Environmental change. A species that can, in contrast to the other species in the ecosystem, successfully survive in a radically changed environment will probably branch into new species that cover the new ecological niches created by the environmental change. An example of adaptive radiation as the result of an environmental change is the rapid spread and development of mammalian species after the extinction of the dinosaurs.
- Geographic isolation. Isolated ecosystems, such as archipelagos and mountain areas, can be colonized by a species which, upon establishing itself, undergoes rapid divergent evolution.
Monotremes and marsupials are examples of geographic isolation. Monotremes evolved before the evolution of placental mammals, and they are found today only in Australia, an island isolated by ocean. Marsupials, which also evolved before the appearance of placental mammals are also common in Australia. In Australia, marsupials evolved to fill many ecological niches that placental mammals fill on other continents.
In science fiction sometimes adaptive radiation of humans is imagined. This often makes for interesting multi-species worlds.
[edit] References
- Wilson, E. et al. Life on Earth, by Wilson,E.; Eisner,T.; Briggs,W.; Dickerson,R.; Metzenberg,R.; O'brien,R.; Susman,M.; Boggs,W.; (Sinauer Associates, Inc., Publishers, Stamford, Connecticut), c 1974. Chapters: The Multiplication of Species; Biogeography, pp 824-877. 40 Graphs, w species pictures, also Tables, Photos, etc. Includes Galápagos Islands, Hawaii, and Australia subcontinent, (plus St. Helena Island, etc.).de:Adaptive Radiation
es:Radiación adaptativa nl:Adaptieve radiatie ja:適応放散 pl:Radiacja adaptacyjna sk:Adaptívna radiácia zh:适应辐射
