Evolutionary radiation: Difference between revisions

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An '''evolutionary radiation''' is an increase in [[taxonomy|taxonomic]] diversity or [[Morphologymorphology (biology)|morphological]] disparity, due to [[adaptation|adaptive]] change or the opening of [[ecospace]].<ref name=Wesley-Hunt2005>{{cite doi|10.1666/0094-8373(2005)031<0035:TMDOCI>2.0.CO;2}}</ref> 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]].<ref name=Schluter2000>{{cite book
| author = Schluter, D.
| year = 2000
==Evolutionary radiation in the fossil record==
 
Much of the work carried out by [[Palaeontologypalaeontology|palaeontologists]] studying evolutionary radiations has been using marine [[invertebrate]] [[fossil]]s simply because these tend to be much more numerous and easy to collect in quantity than large land [[vertebrate]]s such as [[mammal]]s or [[dinosaur]]s. [[Brachiopod]]s, for example, underwent major bursts of evolutionary radiation in the Early [[Cambrian]], Early [[Ordovician]], to a lesser degree throughout the [[Silurian]] and [[Devonian]], and then again during the [[Carboniferous]]. During these periods, different [[species]] of brachiopods independently assumed a similar morphology, and presumably mode of life, to species that had lived millions of years before. This phenomenon, known as [[homeomorphy]] is explained by [[convergent evolution]]: when subjected to similar selective pressures, organisms will often evolve similar adaptations. <ref>''Living and Fossil Brachiopods'' by M. J. S. Rudwick (1970)</ref> Further examples of rapid evolutionary radiation can be observed among [[ammonite]]s, which suffered a series of extinctions from which they repeatedly re-diversified; and [[trilobite]]s which, during the Cambrian, rapidly evolved into a variety of forms occupying many of the [[Ecological niche|niche]]s exploited by [[crustacean]]s today. <ref>''Aquagenesis, The Origins and Evolution of Life in the Sea'' by Richard Ellis (2001)</ref> <ref>''Ammonites'' by Neale Monks & Philip Palmer (2002)</ref> <ref>''Trilobite, Eyewitness to Evolution'' by Richard Fortey (2000)</ref>
 
==Recent evolutionary radiations==
 
A number of groups have undergone evolutionary radiation in relatively recent times. The [[Cichlidaecichlidae|cichlids]] in particular have been much studied by [[biology|biologists]]. In places such as [[Lake Malawi]] they have evolved into a very wide variety of forms, including species that are filter feeders, snail eaters, brood parasites, algal grazers, and fish-eaters. <ref>The Cichlid Fishes: Nature's Grand Experiment in Evolution by George Barlow (2002)</ref> [[Grass]]es have been another success, evolving in parallel with [[grazing]] [[herbivore]]s such as [[horses]] and [[antelope]] .<ref>[http://www.palaeos.com/Cenozoic/Cenozoic.htm Palaeos Cenozoic: The Cenozoic Era<!-- Bot generated title -->].</ref>
 
==References==
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