Robert E. Ricklefs, Department of Biology, University of Pennsylvania, Philadelphia, USA, 'Paleontologists confronting macroevolution',.Science, vol. 199, January 6, 1978, p. 59."They.(some evolutionists).believe that evolution is accelerated in such populations because they contain a small, random sample of the gene pool of the parent population.(founder effect).and therefore can diverge rapidly just by chance and because they can respond to local selection pressures that may differ from those encountered by the parent population. Eventually some of these divergent, peripheral populations are favored by changed environmental conditions.(species selection).and so they increase and spread rapidly into fossil assemblages.

"The punctuated equilibrium model has been widely accepted, not because it has a compelling theoretical basis but because it appears to resolve a dilemma. Apart from the obvious sampling problems inherent to the observations that stimulated the model and apart from its intrinsic.circularity.(one could argue that speciation can occur only when phyletic change is rapid, not vice versa), the model is more ad hoc explanation than theory and it rests on shaky ground."

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