Editing Punctuated equilibrium (section)

===Stasis===
Many hypotheses have been proposed to explain the [[wikt:putative|putative]] causes of stasis. Gould was initially attracted to [[I. Michael Lerner]]'s theories of developmental and genetic homeostasis. However this hypothesis was rejected over time,<ref>[[Stephen Jay Gould|S. J. Gould]] 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge, Massachusetts: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA39 39].</ref> as evidence accumulated against it.<ref name=Futuyma86>Futuyma, Douglas (2005). ''Evolution''. Sunderland, MA: Sinauer Associates, p. 86.</ref> Other plausible mechanisms which have been suggested include: habitat tracking,<ref>{{cite book |last1=Eldredge |first1=Niles |author1-link=Niles Eldredge |last2=Gould |first2=S. J. |title=Evolutionary Biology |chapter=Morphological Transformation, the Fossil Record, and the Mechanisms of Evolution: A Debate |author2-link=Stephen Jay Gould |date=1974 |volume=7 |pages=305–306 |doi=10.1007/978-1-4615-6944-2_8 |isbn=978-1-4615-6946-6 }}</ref><ref>Niles Eldredge (1989). ''Time Frames''. Princeton University Press, pp. 139-141.</ref> [[stabilizing selection]],<ref name="Lieberman">{{cite journal |last1=Lieberman |first1=B. S. |last2=Dudgeon |first2=S. |date=1996 |title=An evaluation of stabilizing selection as a mechanism for stasis |journal=Palaeogeogr. Palaeoclimatol. Palaeoecol. |doi=10.1016/S0031-0182(96)00097-1 |volume=127 |issue=1–4 |pages=229–238|bibcode=1996PPP...127..229L |doi-access=free }}</ref> the Stenseth-Maynard Smith stability hypothesis,<ref>{{cite journal |last1=Stenseth |first1=N. C. |last2=Maynard Smith |first2=John |author-link=John Maynard Smith |date=1984 |title=Coevolution in ecosystems: Red Queen evolution or stasis? |journal=Evolution |doi=10.2307/2408397 |volume=38 |issue=4 |pages=870–880|jstor=2408397 |pmid=28555824 }}</ref> constraints imposed by the nature of subdivided populations,<ref name="Lieberman" /> normalizing clade selection,<ref>[[George C. Williams (biologist)|Williams, G. C.]] (1992). ''Natural Selection: Domains, Levels and Challenges''. New York: Oxford University Press, p. 132.</ref> and [[koinophilia]].<ref name= "Koeslag, 1990">{{cite journal |last1=Koeslag |first1=J. H. |year=1990 |title=Koinophilia groups sexual creatures into species, promotes stasis, and stabilizes social behaviour |journal=Journal of Theoretical Biology |volume=144 |issue=1 |pages=15–35 |doi=10.1016/s0022-5193(05)80297-8 |pmid=2200930 |bibcode=1990JThBi.144...15K }}</ref><ref name= "Koeslag, 1995">Koeslag, J.H. (1995). On the engine of speciation. [http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WMD-45S96TH-5-1&_cdi=6932&_user=613892&_orig=search&_coverDate=12%2F21%2F1995&_sk=998229995&view=c&wchp=dGLbVzb-zSkzS&md5=5ca90c43829c1ac4503e69973e9de576&ie=/sdarticle.pdf ''J. theor. Biol.'' '''177''', 401-409]</ref>

Evidence for stasis has also been corroborated from the genetics of [[sibling species]], species which are morphologically indistinguishable, but whose proteins have diverged sufficiently to suggest they have been separated for millions of years.<ref>{{cite book |last=Maynard Smith |first=John |author-link=John Maynard Smith |year=1989 |title=Did Darwin Get it Right? |location=New York |publisher=Chapman and Hall |page=126}}</ref> Fossil evidence of reproductively isolated extant species of sympatric Olive Shells (''[[Amalda]]'' sp.) also confirm morphological stasis in multiple lineages over three million years.<ref>{{Cite journal |last1=Gemmell |first1=Michael R. |last2=Trewick |first2=Steven A. |last3=Hills |first3=Simon F. K. |last4=Morgan-Richards |first4=Mary |date=2019 |title=Phylogenetic topology and timing of New Zealand olive shells are consistent with punctuated equilibrium |journal=Journal of Zoological Systematics and Evolutionary Research |volume=58 |issue=1 |pages=209–220 |doi=10.1111/jzs.12342 |s2cid=213493738 |doi-access=free }}</ref><ref>{{Cite journal |last=Michaux |first=B. |date=1989 |title=Morphological variation of species through time |journal=Biological Journal of the Linnean Society |volume=38 |issue=3 |pages=239–255 |doi=10.1111/j.1095-8312.1989.tb01577.x}}</ref>

According to Gould, "stasis may emerge as the theory's most important contribution to evolutionary science."<ref>[[Stephen Jay Gould|S. J. Gould]] 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge MA: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA1155 872.]</ref> Philosopher [[Kim Sterelny]] in clarifying the meaning of stasis adds, "In claiming that species typically undergo no further evolutionary change once speciation is complete, they are not claiming that there is no change at all between one generation and the next. Lineages do change. But the change between generations does not accumulate. Instead, over time, the species wobbles about its [[Phenotype|phenotypic]] mean. [[Jonathan Weiner]]'s ''[[The Beak of the Finch]]'' describes this very process."<ref>Sterelny, Kim (2007). ''[[Dawkins vs. Gould|Dawkins vs. Gould: Survival of the Fittest]]''. Cambridge, U.K.: Icon Books, p. 96.</ref>