DragonflyIssuesInEvolution13 Wiki

How scientists know about punctuated equilibria

 Punctuated Equilibrium is an evolutionary theory first suggested by Stephen Jay Gould and Niles Eldridge (www.pbs.org).  The theory states that evolution takes place in a short amount of time in a species history.  These changes take place in rapid bursts (www.evolution.berkely.edu).  The theory takes place in 7 steps from stasis to rapid bursts to reintroduction.

In contrast, evolutionary biologists like Jay Gould have also discussed the theory of "phyletic gradualism" which attributes speciation to a "slow and steady transformation of entire populations" (Eldredge and Gould, 1972). Much debate surrounds the topic of punctuated equilibrium as a mode of speciation, rather than just being a result of gaps that exist in the fossil record.  


An example of punctuated equilibrium is the fossil mollusks of East Africa (Hicke, J.)


Hicke, J. www.webpages.uidaho.edu/~jhicke/.../chapter_09.1_evolution.pdf



Eldredge, N. and Gould, S.J. (1972). Punctuated equilibria: an alternative to phyletic gradualism. In Schopf, Thomas J.M. (ed.). Models in Paleobiology. San Francisco: Freeman, Cooper and Company, pp. 82-115.