Search results
Results from the WOW.Com Content Network
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.
The Bak–Sneppen model is a simple model of co-evolution between interacting species. It was developed to show how self-organized criticality may explain key features of the fossil record, such as the distribution of sizes of extinction events and the phenomenon of punctuated equilibrium. It is named after Per Bak and Kim Sneppen.
The theory of punctuated equilibrium developed by Stephen Jay Gould and Niles Eldredge and first presented in 1972 [61] is often mistakenly drawn into the discussion of transitional fossils. [62] This theory, however, pertains only to well-documented transitions within taxa or between closely related taxa over a geologically short period of time.
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.
Gould's initial work on punctuated equilibrium was coauthored with Niles Eldredge. [20] Gould's model of punctuated equilibrium drew attention to episodic bursts of evolutionary change followed by periods of morphological stability. He challenged the conventional model of gradual, continuous change - called phyletic gradualism. [21]
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]
Punctuated gradualism is considered to be a variation of these models, lying somewhere in between the phyletic gradualism model and the punctuated equilibrium model. It states that speciation is not needed for a lineage to rapidly evolve from one equilibrium to another but may show rapid transitions between long-stable states.
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.