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Information about Adaptive Radiation



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 natural selection, successful and novel adaptation, and sometimes by mutation (heritable/genetic variation).

Causes of adaptive radiation

Opportunity

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, a 'continent country'. 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.

Richard Leakey (see below) wrote, "Biologists who have studied the fossil record know that when a new species evolves with a novel adaptation, there is often a burgeoning of descendent species over the next few million years expressing various themes on that initial adaptation - a burgeoning known as adaptive radiation. The Cambridge University anthropologist Robert Foley has calculated that if the evolutionary history of the bipedal apes followed the usual pattern of adaptive radiation, at least sixteen species should have existed between the group's origin 7 million years ago and today."

Extinction

Adaptive radiation can also occur after mass extinctions. The best example of this is after the Permian-Triassic extinction event, where biodiversity increased massively in the Triassic. The end of the Ediacaran and the beginnings of multicellular life lead to adaptive radiations and the genesis of new phyla in the Cambrian period.

Adaptive radiation in popular culture

In science fiction sometimes adaptive radiation of humans is imagined. This often makes for interesting multi-species worlds.

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.).
  • Leakey,Richard. The Origin of Humankind - on adaptive radiation in biology and human evolution, pp. 28-32, 1994, Orion Publishing.


Speciation is the evolutionary process by which new biological species arise. There are four modes of natural speciation, based on the extent to which speciating populations are geographically isolated from one another:
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species is one of the basic units of biological classification. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
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niche (pronounced nich, neesh or nish)[] is a term describing the relational position of a species or population in its ecosystem[1]. The ecological niche describes how an organism or population responds to the distribution of resources and competitors (e. g.
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Natural selection is the process by which favorable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavorable traits that are heritable become less
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mutations are changes to the base pair sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can occur deliberately
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ecosystem is a natural unit consisting of all plants, animals and micro-organisms in an area functioning together with all the non-living physical factors of the environment.
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archipelago is a chain or cluster of islands. The word archipelago literally means "chief sea", from Greek arkhon (arkhi-) ("leader") and pelagos ("sea").
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mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is generally steeper than a hill, but there is no universally accepted standard definition for the height of a mountain or a hill although a mountain usually has an identifiable
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Divergent evolution occurs when two or more biological characteristics have a common evolutionary origin but have diverged over evolutionary time. This is also known as adaptation or adaptive evolution.
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Monotremata
C.L. Bonaparte, 1837

Families

†Kollikodontidae
Ornithorhynchidae
Tachyglossidae
†Steropodontidae
Monotremes (from the Greek monos 'single' + trema
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Marsupialia
Illiger, 1811

Orders
  • Didelphimorphia
  • Paucituberculata
  • Microbiotheria
  • Dasyuromorphia
  • Peramelemorphia
  • Notoryctemorphia
  • Diprotodontia
  • Sparassodonta (extinct)
  • Yalkaparidontia (extinct)
Marsupials
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continent is one of several large landmasses on Earth. They are generally identified by convention rather than any strict criteria, but seven areas are commonly regarded as continents – they are (from largest in size to smallest): Asia, Africa, North America, South America,
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Richard Erskine Frere Leakey (born 19 December 1944 in Nairobi, Kenya), is a Kenyan paleontologist and conservationist. He is second of the three sons of the archaeologists Louis Leakey and Mary Leakey, and is the younger brother of Colin Leakey.
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Robert A. Foley is Director of the Leverhulme Centre for Human Evolutionary Studies and Leverhulme Professor of Human Evolution at the University of Cambridge.

Foley is the leading light of the Cambridge school in evolutionary biology which argues, within the context of the
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For the Big Finish Productions audio play, see .
An extinction event (also known as: mass extinction; extinction-level event, ELE) is a sharp decrease in the number of species in a relatively short period of time.
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Biodiversity is the variation of life forms within a given ecosystem, biome or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems.
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The Triassic is a geologic period that extends from about 251 to 199 Ma (million years ago). As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events.
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Cryogenian

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Multicellular organisms are organisms consisting of more than one cell, and having differentiated cells that perform specialized functions. Most life that can be seen with the naked eye is multicellular, as are all members of the kingdoms Plantae and Animalia (except for
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The Cambrian is a major division of the geologic timescale that begins about 542 ± 1.0 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3 ± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004).
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Science fiction (abbreviated SF or sci-fi
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fictional realm, imaginary realm, fictional world, imaginary world or imaginary universe. Most fictional universes are based directly or indirectly on our own universe.
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State Party  Ecuador
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Criteria vii, viii, ix, x
Reference 1
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Flag of Hawaii Seal of Hawaii
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