Adaptive Radiation - Wikipedia

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.wikipedia.org/wiki/Adaptive_radiation

Four of the 14 finch species found on

the Galpagos Archipelago, are

thought to have evolved by anadaptive radiation that diversified

their beak shapes to adapt them to

different food sources.

Adaptive radiationFrom Wikipedia, the free encyclopedia

In evolutionary biology, adaptive radiation is the evolution of

ecological and phenotypic diversity within a rapidly multiplying

lineage.[1] Starting with a recent single ancestor, this process results in

the speciation and phenotypic adaptation of an array of species

exhibiting different morphological and physiological traits with which

they can exploit a range of divergent environments. [1]

Adaptive radiation, a characteristic example of cladogenesis, can be

graphically illustrated as a "bush", or clade, of coexisting species (on

the tree of life). [2]

Contents

1 Identification2 Causes

2.1 Innovation2.2 Opportunity

3 See also4 References5 Further reading

Identification

Four features can be used to identify an adaptive radiation:[1]

1. A common ancestry of component species: specifically a recentancestry. Note that this is not the sameas a monophyly in which all descendants of a common ancestor are included.

2. A phenotype-environment correlation: a significantassociation between environments and themorphological and physiological traits used to exploit those environments.

3. Trait utility: the performance or fitness advantages of trait values in their corresponding environments.4. Rapid speciation: presence of one or more bursts in the emergence of new species around the time that

ecological and phenotypic divergence is underway.

Causes

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 va


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increase in the range of foodstuffs which can be fed on. Evolution of this character has thus increased the

number of ecological niches available to mammals. The trait arose a number of times in different groups

during the Cenozoic, and in each instance was immediately followed by an adaptive radiation. [3] Birds find

other ways to provide for each other, i.e. the evolution of flight opened new avenues for evolution to explore

initiating an adaptive radiation.[4] Other examples include placental gestation (for eutherian mammals), or

bipedal locomotion (in hominins).[2]

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, an isolated lake which formed recently in the African rift valley, over 300 species of cichlid

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 theCretaceous, and of brachiopods by bivalves at the Permo-Triassic boundary.

See also

Evolutionary radiationa more general term to describe any radiationCambrian explosionthe most famous evolutionary radiationList of adaptive radiated Hawaiian honeycreepers by formList of adaptive radiated marsupials by form

References

1. ^ abc Schluter, Dolph (2000). The Ecology of Adaptive Radiation (http://www.google.com/books?

id=Q1wxNmLAL10C&pg=PA10) . Oxford University Press. pp. 1011. ISBN 0-19-850523-X.

http://www.google.com/books?id=Q1wxNmLAL10C&pg=PA10.

2. ^ ab Lewin, Roger (2005). Human evolution : an illustrated introduction (http://books.google.com/books?

doi=SopsLRo1QyUC&pg=PA21) (5th ed.). p. 21. ISBN 1-4051-0378-7. http://books.google.com/books?

doi=SopsLRo1QyUC&pg=PA21.

3. ^

4. ^ Feduccia, Alan (1999). The Origin and Evolution of Birds.

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 824877. 40Graphs, w species pictures, also Tables, Photos, etc. Includes Galpagos Islands, Hawaii, andAustralia subcontinent, (plus St. Helena Island, etc.).


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Leakey, Richard. The Origin of Humankindon adaptive radiation in biology and humanevolution, pp. 2832, 1994, Orion Publishing.Grant, P.R. 1999. The ecology and evolution of Darwin's Finches. Princeton University Press,Princeton, NJ.Mayr, 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: 105136Gavrilets, S. and A. Vose. 2005.Dynamic patterns of adaptive radiation Proc. Natl. Acad. Sci.USA 102: 18040-18045.

Gavrilets, S. and A. Vose. 2009.Dynamic patterns of adaptive radiation: evolution of matingpreferences. In Butlin, RK, J Bridle, and D Schluter (eds) Speciation and Patterns of Diversity,Cambridge University Press, pp. 102-126.

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