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Phyletic Gradualism
A theory of evolution, supported by Darwin, which states that evolution is a gradual process that proceeds slowly but constantly through a series of small changes.
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Punctuated Equilibrium
A theory of evolution, proposed by Niles Eldredge and Stephen J. Gould, which disagrees with phyletic gradualism and states that evolution is not gradual, but rather proceeds by means of bursts of change separated by long periods of relative stasis.