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Punctuated equilibrium is commonly contrasted with phyletic gradualism, the idea that evolution generally occurs uniformly by the steady and gradual transformation of whole lineages . [ 2 ] In 1972, paleontologists Niles Eldredge and Stephen Jay Gould published a landmark paper developing their theory and called it punctuated equilibria . [ 1 ]
Gradualism is often confused with the concept of phyletic gradualism. It is a term coined by Stephen Jay Gould and Niles Eldredge to contrast with their model of punctuated equilibrium , which is gradualist itself, but argues that most evolution is marked by long periods of evolutionary stability (called stasis), which is punctuated by rare ...
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.
Reviewing the history of macroevolutionary theories, the American evolutionary biologist Douglas J. Futuyma notes that since 1970, two very different alternatives to Darwinian gradualism have been proposed, both by Stephen Jay Gould: mutationism, and punctuated equilibria.
One of the most compelling examples of animal grief she discusses is the case of Tahlequah, an orca whose “grief swim” in 2018, and now again in 2025, has captured global attention and ...
Punctuated equilibrium and phyletic gradualism are not mutually exclusive (as Simpson's work demonstrates), and examples of each have been documented in different lineages. The debate between these two models is often misunderstood by non-scientists, and according to Richard Dawkins has been oversold by the media. [45]
This would result in increased cases of speciation through cladogenesis and true extinction, with fewer cases of Pseudoextinction. Nearly all species undergo true extinction under the model of punctuated equilibrium. [15] Charles Darwin proposed the idea of stasis in his book, On the Origin of Species. He suggested that species spend the ...