Punctuated equilibrium: Difference between revisions

The fossil record includes well documented examples of both phyletic gradualism{{Citation needed|reason=The previous citation provided no evidence for gradualism, and merely contrasted Darwin's models with those of Eldrige/Gould. Need concrete evidence here|date=October 2018}} and punctuational evolution.<ref name="BentonHarper" /> As such, much debate persists over the prominence of stasis in the fossil record.<ref name="Futuyma86" /><ref>Erwin, D. H. and R. L. Anstey (1995) ''New approaches to speciation in the fossil record''. New York : Columbia University Press.</ref> Before punctuated equilibrium, most evolutionists considered stasis to be rare or unimportant.<ref name="Mayr1992" /><ref>Gould, S. J. 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge MA: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA1154 875].</ref><ref>{{cite journal |last1=Wake |first1=David B. |last2=Roth |first2=G. |last3=Wake |first3=M. H. |date=1983 |title=On the problem of stasis in organismal evolution |journal=Journal of Theoretical Biology |doi=10.1016/0022-5193(83)90335-1 |volume=101 |issue=2 |page=212}}</ref> The paleontologist [[George Gaylord Simpson]], for example, believed that phyletic gradual evolution (called ''horotely'' in his terminology) comprised 90% of evolution.<ref>Simpson, G. G. (1944). ''Tempo and Mode in Evolution''. Columbia University Press. New York, p. 203.</ref> More modern studies,<ref name="Campbell">Campbell, N.A. (1990) ''Biology'' p. 450–451, 487–490, 499–501. Redwood City CA: Benjamin Cummings Publishing Company.</ref><ref name="Gould&Eldredge1977" /><ref name="McCarthy">McCarthy, T. & Rubridge, B. (2005) ''The Story of Earth and Life''. Cape Town: Struik Publishers. {{ISBN|1-77007-148-2}}.</ref> including a [[meta-analysis]] examining 58 published studies on speciation patterns in the fossil record showed that 71% of species exhibited stasis,<ref>{{cite journal|last1=Neto|first1=SGB|last2=AF|first2=E|last3=S|first3=Mariana|date=2017|title=Speciation in real time and historical-archaeological and its absence in geological time|url=https://www.academia.edu/39120976|journal=Academia Journal of Scientific Research|language=en|doi=10.15413/ajsr.2017.0413|doi-broken-date=2020-05-29|issn=2315-7712}}</ref> and 63% were associated with punctuated patterns of evolutionary change.<ref>Erwin, D.H. and Anstey, R.L (1995). [http://somosbacteriasyvirus.com/speciation.pdf "Speciation in the fossil record."] In Erwin, D.H. & Anstey, R.L. (eds). ''New Approaches to Speciation in the Fossil Record''. Columbia University Press, New York, pp. 11–39.</ref> According to [[Michael Benton]], "it seems clear then that stasis is common, and that had not been predicted from modern genetic studies."<ref name="BentonHarper">Benton, Michael and David Harper (2009) ''Introduction to Paleobiology and the Fossil Record'' New York: John Wiley & Sons, [https://books.google.com/books?id=ZQ1U9wmoensC&pg=PT227 pp. 123-124.]</ref> A paramount example of evolutionary stasis is the fern ''[[Osmunda claytoniana]]''. Based on paleontological evidence it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least 180 million years.<ref name="pmid24653037">{{cite journal |last1=Bomfleur |first1=B. |last2=McLoughlin |first2=S. |last3=Vajda |first3=V. |date=March 2014 |title=Fossilized nuclei and chromosomes reveal 180 million years of genomic stasis in royal ferns |journal=Science |pmid=24653037 |doi=10.1126/science.1249884 |volume=343 |issue=6177 |pages=1376–7|url=http://nrm.diva-portal.org/smash/get/diva2:719316/FULLTEXT01 |bibcode=2014Sci...343.1376B }}</ref>