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Adaptive radiation

 
Adaptive Radiation

 
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An adaptive radiation is a rapid evolutionary radiation
Evolutionary radiation

An evolutionary radiation is an increase in taxonomy diversity or Morphology disparity, due to adaptation change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations....
 characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage. Phenotypes adapt in response to the environment, with new and useful traits arising.






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Encyclopedia


Darwin's Finches
An adaptive radiation is a rapid evolutionary radiation
Evolutionary radiation

An evolutionary radiation is an increase in taxonomy diversity or Morphology disparity, due to adaptation change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations....
 characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage. Phenotypes adapt in response to the environment, with new and useful traits arising. This is an evolution
Evolution

In biology, evolution is change in the heritability trait of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection....
ary process driven by natural selection
Natural selection

Natural selection is the process by which favorable heritable trait become more common in successive generations of a population of Reproduction organisms, and unfavorable heritable traits become less common, due to differential reproduction of genotypes....
.

Causes of adaptive radiation


Innovation

The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible. A classic example is the evolution of a fourth cusp in the mammalian tooth. This trait permits a vast increase in the range of foodstuffs which can be utilized, with species able to specialize on feeding on a range of foodstuffs. The trait arose a number of times in different groups during the Cenozoic
Cenozoic

The Cenozoic Era...
, and in each instance was immediately followed by an adaptive radiation. Birds find other ways to provide for each other, ie. the evolution of flight opened new avenues for evolution to explore, initiating an adaptive radiation.

Opportunity

Adaptive radiations often occur as a result of an organism arising in an environment with unoccupied niches, such as a newly formed lake or isolated island chain. The colonizing population may diversify rapidly to take advantage of all possible niches.

In Lake Victoria
Lake Victoria

Lake Victoria or Victoria Nyanza is one of the Great Lakes of Africa.Lake Victoria is 68,800 square kilometres in size, making it the continent's largest lake, the largest tropical lake in the world, and the second widest fresh water lake in the world in terms of surface area ....
, an isolated lake which formed recently in the African rift valley, over 300 species of cichlid
Cichlid

Cichlids are fish from the family Cichlidae in the order Perciformes. The family Cichlidae, a major family of perciform fish, is both large and diverse....
 fish adaptively radiated from one parent species in just 15,000 years.

Adaptive radiations commonly follow mass extinctions: following an extinction, many niches are left vacant. A classic example of this is the replacement of the non-avian dinosaurs with mammals at the end of the Cretaceous, and of brachiopod
Brachiopod

Brachiopods are a small Phylum of benthic invertebrates. Also known as lamp shells , "brachs" or Brachiopoda, they are Sessility , two-valved, Marine animals with an external morphology superficially resembling Bivalvias to which they are not closely related....
s by bivalves at the Permo-Triassic boundary..

1. Species A migrates from the mainland to the first island.

2. Isolated from the mainland, species A evolves to species B.
3. Species B migrates to the second island.

4. Species B evolves in species C.
5. Species C recolonizes the first islands, but is now unable to reproduce with species B.
6. Species C migrates to the third island.

7. Species C evolves into species D.
8. Species D migrates to the first and second island.

9. Species D evolves to species E.

This process could go on indefinitely until a large diversity is reached.


See also

  • Evolutionary radiation
    Evolutionary radiation

    An evolutionary radiation is an increase in taxonomy diversity or Morphology disparity, due to adaptation change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations....
     – a more general term to describe any radiation
  • Cambrian explosion
    Cambrian explosion

    The Cambrian explosion or Cambrian radiation was the seemingly rapid appearance of most major groups of complex animals around , as evidenced by the fossil record....
     – the most famous evolutionary radiation


Further reading

  • 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
    Galápagos Islands

    Gal?pagos Islands are an archipelago of Island#Volcanic islands distributed around the equator in the Pacific Ocean, 972 km west of continental Ecuador....
    , Hawaii
    Hawaii

    File:Pahoehoe and Aa flows at Hawaii.jpgThe State of Hawaii is a U.S. state in the United States, located on an archipelago in the central Pacific Ocean southwest of the continental United States, southeast of Japan, and northeast of Australia....
    , and Australia
    Australia (continent)

    Australia Sahul is the smallest of the geographic continents, though not of geological continents. There is no universally accepted definition of the word "continent"; the lay definition is "One of the main continuous bodies of land on the earth's surface." ....
     subcontinent, (plus St. Helena Island, etc.).
  • Leakey,Richard. The Origin of Humankind – on adaptive radiation in biology and human evolution, pp. 28–32, 1994, Orion Publishing.
  • Grant, P.R. 1999. The ecology and evolution of Darwin's Finches. Princeton University Press, Princeton, NJ.
  • Mayer, Ernst. 2001. What evolution is. Basic Books, New York, NY.
  • Kemp, A.C. 1978. A review of the hornbills: biology and radiation. The Living Bird 17: 105–136.