Editing Peripatric speciation (section)

=== Centrifugal speciation ===
William Louis Brown, Jr. proposed an alternative model of peripatric speciation in 1957 called centrifugal speciation. This model contrasts with peripatric speciation by virtue of the origin of the genetic novelty that leads to reproductive isolation.<ref name="Gavrilets">{{Citation |title=Patterns of Parapatric Speciation |author=Sergey Gavrilets, Hai Li, & Michael D. Vose |journal=Evolution |year=2000 |volume=54 |issue=4 |pages=1126–1134 |doi=10.1554/0014-3820(2000)054[1126:pops]2.0.co;2|pmid=11005282 |citeseerx=10.1.1.42.6514 |s2cid=198153997 }}</ref> A population of a species experiences periods of geographic range expansion followed by periods of contraction. During the contraction phase, fragments of the population become isolated as small [[Refugium (population biology)|refugial]] populations on the periphery of the central population. Because of the large size and potentially greater genetic variation within the central population, [[mutation]]s arise more readily. These mutations are left in the isolated peripheral populations, promoting reproductive isolation. Consequently, Brown suggested that during another expansion phase, the central population would overwhelm the peripheral populations, hindering speciation. However, if the species finds a specialized ecological niche, the two may coexist.<ref name="DJH">{{cite book |author=Daniel J. Howard |title=Encyclopedia of Life Sciences |chapter=Speciation: Allopatric |journal=eLS |date=2003 |doi=10.1038/npg.els.0001748|isbn=978-0470016176 }}</ref><ref>{{Citation |title=Centrifugal speciation |author=W. L. Brown Jr. |journal=Quarterly Review of Biology |year=1957 |volume=32 |issue=3 |pages=247–277 |doi=10.1086/401875|s2cid=225071133 }}</ref> The phylogenetic signature of this model is that the central population becomes [[Synapomorphy|derived]], while the peripheral isolates stay plesiomorphic<ref name="JKFrey" />—the reverse of the general model. In contrast to centrifugal speciation, peripatric speciation has sometimes been referred to as '''centripetal speciation''' (see figures 1 and 2 for a contrast).<ref>{{Citation |title=Interview with John C. Briggs, recipient of the 2005 Alfred Russel Wallace award |url=https://escholarship.org/uc/item/8jg516kj |author=Brian W. Bowen |journal=Frontiers of Biogeography |year=2010 |volume=2 |issue=3 |pages=78–80 |issn=1948-6596 }}</ref> Centrifugal speciation has been largely ignored in the scientific literature, often dominated by the traditional model of peripatric speciation.<ref name="Briggs">{{Citation |title=Centrifugal speciation and centres of origin |author=John C. Briggs |journal=Journal of Biogeography |year=2000 |volume=27 |issue=5 |pages=1183–1188 |doi=10.1046/j.1365-2699.2000.00459.x|bibcode=2000JBiog..27.1183B |s2cid=86734208 }}</ref><ref name="Gavrilets" /><ref name="JKFrey" /> Despite this, Brown cited a wealth of evidence to support his model, of which has not yet been refuted.<ref name="DJH" />

''[[Peromyscus]] polionotus'' and ''P. melanotis'' (the peripherally isolated species from the central population of ''P. maniculatus'') arose via the centrifugal speciation model.<ref>{{Citation |title=Chromosomal Evolution and the Mode of Speciation in Three Species of Peromyscus |author=Ira F. Greenbaum, Robert J. Baker & Paul R. Ramsey |journal=Evolution |year=1978 |volume=32 |issue=3 |pages=646–654 |pmid=28567964 |doi=10.1111/j.1558-5646.1978.tb04609.x |s2cid=27865356 |doi-access=free }}</ref> Centrifugal speciation may have taken place in [[tree kangaroo]]s, South American frogs (''[[Ceratophrys]]''), shrews (''[[Crocidura]]''), and primates (''[[Sumatran surili|Presbytis melalophos]]'').<ref name="Briggs" /> [[John C. Briggs]] associates centrifugal speciation with [[Center of origin|centers of origin]], contending that the centrifugal model is better supported by the data, citing species patterns from the proposed 'center of origin' within the [[Indo-Pacific|Indo-West Pacific]]<ref name="Briggs" />