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In evolutionary biology, punctuated equilibrium (also called punctuated equilibria) is a theory that proposes that once a species appears in the fossil record, the population will become stable, showing little evolutionary change for most of its geological history. [1] This state of little or no morphological change is called stasis.
According to Gould, punctuated equilibrium revised a key pillar "in the central logic of Darwinian theory." [17] Some evolutionary biologists have argued that while punctuated equilibrium was "of great interest to biology generally," [42] it merely modified neo-Darwinism in a manner that was fully compatible with what had been known before. [43]
The punctuated equilibrium model of policy change was first presented by Frank Baumgartner and Bryan Jones in 1993, [1] and has increasingly received attention in historical institutionalism. [3] The model states that policy generally changes only incrementally due to several restraints, namely the "stickiness" of institutional cultures, vested ...
Sudden jumps with apparent gaps in the fossil record have been used as evidence for punctuated equilibrium. Such jumps can be explained either by macromutation or simply by relatively rapid episodes of gradual evolution by natural selection, since a period of say 10,000 years barely registers in the fossil record.
A period of stasis then occurs until the species either becomes extinct or splits again. Gould argued that punctuated equilibrium challenges the gradual change expected by extrapolationists. In the case of Hominid evolution, there is the evolutionary trend of marked increase in brain size.
Punctuated equilibrium [ edit ] In the 1980s, the American palaeontologists Stephen Jay Gould and Niles Eldredge argued for an extended synthesis based on their idea of punctuated equilibrium , the role of species selection shaping large scale evolutionary patterns and natural selection working on multiple levels extending from genes to species.
A Polish woman who claimed to be missing Madeleine McCann was arrested upon landing in the UK. Julia Wandelt, who also goes by Julia Wendell and Julia Faustyna, was taken into custody upon ...
The word phyletic derives from the Greek φυλετικός phūletikos, which conveys the meaning of a line of descent. [2] Phyletic gradualism contrasts with the theory of punctuated equilibrium, which proposes that most evolution occurs isolated in rare episodes of rapid evolution, when a single species splits into two distinct species, followed by a long period of stasis or non-change.