Editing Punctuated equilibrium (section)

==Darwin's theory==
The sudden appearance of most species in the geologic record and the lack of evidence of substantial gradual change in most [[species]]—from their initial appearance until their extinction—has [[Speciation#Darwin's dilemma: Why do species exist?|long been noted]], including by [[Charles Darwin]], who appealed to the imperfection of the record as the favored explanation.<ref>Darwin, Charles (1859). ''[[On the Origin of Species]]''. London: John Murray, p. 301.</ref><ref>Darwin, Charles (1871). ''[[The Origin of Species]]''. London: John Murray, p. 119-120.</ref> When presenting his ideas against the prevailing influences of [[catastrophism]] and [[progressive creationism]], which envisaged species being supernaturally created at intervals, Darwin needed to forcefully stress the gradual nature of [[evolution]] in accordance with the [[gradualism]] promoted by his friend [[Charles Lyell]]. He privately expressed concern, noting in the margin of his 1844 ''Essay'', "Better begin with this: If species really, after catastrophes, created in showers world over, my theory false."<ref name=VQR>Eldredge, Niles (2006) [http://www.vqronline.org/articles/2006/spring/eldredge-confessions-darwinist/ "Confessions of a Darwinist."] {{Webarchive|url=https://web.archive.org/web/20131224110620/http://www.vqronline.org/articles/2006/spring/eldredge-confessions-darwinist/ |date=2013-12-24 }} ''[[The Virginia Quarterly Review]]'' 82 (Spring): 32-53.</ref>

It is often incorrectly assumed that he insisted that the rate of change must be constant, or nearly so, but even the first edition of ''[[On the Origin of Species]]'' states that "Species of different genera and classes have not changed at the same rate, or in the same degree. In the oldest tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms... The Silurian ''Lingula'' differs but little from the living species of this genus". ''[[Lingula (genus)|Lingula]]'' is among the few brachiopods surviving today but also known from fossils over 500 million years old.<ref>Darwin, Charles (1859). ''On the Origin of Species''. London: John Murray. [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=331 p. 313].</ref> In the fourth edition (1866) of ''On the Origin of Species'' Darwin wrote that "the periods during which species have undergone modification, though long as measured in years, have probably been short in comparison with the periods during which they retain the same form."<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F387&pageseq=583 p. 551].</ref> Thus punctuationism in general is consistent with Darwin's conception of evolution.<ref name=VQR/>

According to early versions of punctuated equilibrium, "peripheral isolates" are considered to be of critical importance for speciation. However, Darwin wrote, "''I can by no means agree'' ... that immigration and isolation are necessary elements. ... Although isolation is of great importance in the production of new species, on the whole I am inclined to believe that largeness of area is still more important, especially for the production of species which shall prove capable of enduring for a long period, and of spreading widely."<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?itemID=F387&viewtype=text&pageseq=1 pp. 120-121.]</ref>

The importance of isolation in forming species had played a significant part in Darwin's early thinking, as shown in his ''Essay'' of 1844. But by the time he wrote the ''Origin'' he had downplayed its importance.<ref name=VQR/> He explained the reasons for his revised view as follows:
<blockquote>Throughout a great and open area, not only will there be a greater chance of favourable variations, arising from the large number of individuals of the same species there supported, but the conditions of life are much more complex from the large number of already existing species; and if some of these species become modified and improved, others will have to be improved in a corresponding degree, or they will be exterminated. Each new form, also, as soon as it has been improved, will be able to spread over the open and continuous area, and will thus come into competition with many other forms&nbsp;... the new forms produced on large areas, which have already been victorious over many competitors, will be those that will spread most widely, and will give rise to the greatest number of new varieties and species. They will thus play a more important role in the changing history of the organic world.<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?itemID=F387&viewtype=text&pageseq=1 pp. 121-122.]</ref></blockquote>

Thus punctuated equilibrium is incongruous with some of Darwin's ideas regarding the specific mechanisms of evolution, but generally accords with Darwin's theory of evolution by natural selection.<ref name=VQR/><ref name="ComesOfAge">{{Citation |last1=Gould |first1=Stephen Jay |author-link1=Stephen Jay Gould |last2=Eldredge |first2=Niles |author-link2=Niles Eldredge |date=1993 |title=Punctuated equilibrium comes of age |journal=Nature |doi=10.1038/366223a0 |pmid=8232582|volume=366 |issue=6452 |pages=223–227 |url=http://www.stephenjaygould.org/library/gould_comes-of-age.html|bibcode=1993Natur.366..223G |s2cid=4253816 }}</ref>