Editing Adaptive radiation (section)

== Conditions ==
Adaptive radiations are thought to be triggered by an ecological opportunity<ref name=":0">{{Cite journal|last1=Yoder|first1=J. B.|last2=Clancey|first2=E.|last3=Des Roches|first3=S.|last4=Eastman|first4=J. M.|last5=Gentry|first5=L.|last6=Godsoe|first6=W.|last7=Hagey|first7=T. J.|last8=Jochimsen|first8=D.|last9=Oswald|first9=B. P.|last10=Robertson|first10=J.|last11=Sarver|first11=B. A. J.|date=2010|title=Ecological opportunity and the origin of adaptive radiations: Ecological opportunity and origin of adaptive radiations|journal=Journal of Evolutionary Biology|language=en|volume=23|issue=8|pages=1581–1596|doi=10.1111/j.1420-9101.2010.02029.x|pmid=20561138|s2cid=25334971|doi-access=free}}</ref> or a new adaptive zone.<ref name=":1">{{Cite journal|last=Simpson|first=G|title=Tempo and Mode in Evolution|journal=Transactions of the New York Academy of Sciences|publisher=Columbia University Press|year=1949|volume=8|pages=45–60|location=New York|doi=10.1111/j.2164-0947.1945.tb00215.x|pmid=21012247}}</ref> Sources of ecological opportunity can be the loss of antagonists ([[Competition|competitors]] or [[Predation|predators]]), the evolution of a key innovation, or dispersal to a new environment. Any one of these ecological opportunities has the potential to result in an increase in population size and relaxed [[Stabilizing selection|stabilizing]] (constraining) selection. As [[genetic diversity]] is positively [[Correlation and dependence|correlated]] with population size<ref>{{Cite journal|last1=Hague|first1=M T J|last2=Routman|first2=E J|date=2016|title=Does population size affect genetic diversity? A test with sympatric lizard species|url= |journal=Heredity|language=en|volume=116|issue=1|pages=92–98|doi=10.1038/hdy.2015.76|issn=0018-067X|pmc=4675878|pmid=26306730}}</ref> the expanded population will have more genetic diversity compared to the ancestral population. With reduced stabilizing selection [[Phenotype|phenotypic]] diversity can also increase. In addition, intraspecific competition will increase, promoting divergent selection to use a wider range of resources. This ecological release provides the potential for [[ecological speciation]] and thus adaptive radiation.<ref name=":0" />

Occupying a new environment might take place under the following conditions:<ref name="Stroud">{{Cite journal|last=Stroud and Losos|date=2016|title=Ecological Opportunity and Adaptive Radiation|journal=Annual Review of Ecology, Evolution, and Systematics|volume=47|pages=507–532|doi=10.1146/annurev-ecolsys-121415-032254|doi-access=free}}</ref>

#A new habitat has opened up: a volcano, for example, can create new ground in the middle of the ocean. This is the case in places like [[Hawaii]] and the [[Galápagos Islands|Galapagos]]. For aquatic species, the formation of a large new lake habitat could serve the same purpose; the tectonic movement that formed the [[East African Rift]], ultimately leading to the creation of the [[Rift Valley lakes|Rift Valley Lakes]], is an example of this. An [[extinction event]] could effectively achieve this same result, opening up niches that were previously occupied by species that no longer exist.
#This new habitat is relatively isolated. When a volcano erupts on the mainland and destroys an adjacent forest, it is likely that the terrestrial plant and animal species that used to live in the destroyed region will recolonize without evolving greatly. However, if a newly formed habitat is isolated, the species that colonize it will likely be somewhat random and uncommon arrivals.
#The new habitat has a wide availability of niche space. The rare colonist can only adaptively radiate into as many forms as there are niches.<ref name=":1" />

===Relationship between mass-extinctions and mass adaptive radiations===
{{See also|Cambrian explosion#End-Ediacaran mass extinction}}
{{Phanerozoic biodiversity}}
{{Expand section|date=January 2021}}
A 2020 study found there to be no direct causal relationship between the proportionally most comparable mass radiations and [[mass extinction|extinctions]] in terms of "co-occurrence of species", substantially challenging the hypothesis of "creative mass extinctions".<ref>{{cite news |last1=Black |first1=Riley |title=Earth's Biodiversity Bursts Do Not Follow Expected Pattern |url=https://www.scientificamerican.com/article/earths-biodiversity-bursts-do-not-follow-expected-pattern/ |access-date=17 January 2021 |work=Scientific American |language=en}}</ref><ref>{{cite news |title=Artificial intelligence finds surprising patterns in Earth's biological mass extinctions |url=https://phys.org/news/2020-12-artificial-intelligence-patterns-earth-biological.html |access-date=17 January 2021 |work=phys.org |language=en}}</ref><ref>{{cite journal |last1=Hoyal Cuthill |first1=Jennifer F. |last2=Guttenberg |first2=Nicholas |last3=Budd |first3=Graham E. |title=Impacts of speciation and extinction measured by an evolutionary decay clock |journal=Nature |date=December 2020 |volume=588 |issue=7839 |pages=636–641 |doi=10.1038/s41586-020-3003-4 |pmid=33299185 |bibcode=2020Natur.588..636H |s2cid=228090659 |url=https://www.nature.com/articles/s41586-020-3003-4 |access-date=17 January 2021 |language=en |issn=1476-4687}}</ref>