punctuated equlibrium vs gradual change whats the difference in the theory behind these two kinds of evolution

Question

does anyone know any good websites or books on the subject

Answer 1

Puntuated equilibrium; evolutionary change occurs due to dramatic shifts in the environment or the loss of most of a population in a catastrophe. Ecosystems are effectively rebuilt from scratch with succession occuring. Eg; KT boundry event, Anak Krakatoa.

Gradualism; organisms and their environment coevolve over a period of time producing a stable ecosystem ecosystem overall.
Eg. Cheetah and Gazelle

Answer 2

The best website for all questions about evolution is http://www.talkorigins.org - their specific punctuated equilibria FAQ is at http://www.talkorigins.org/faqs/punc-eq.html

Briefly, PE is a theory originally proposed by Stephen J Gould and Niles Eldredge to explain the fact that in the fossil record we observe fairly long periods of stasis, then seemingly abrupt changes. One part of this explanation is that minor mutations build up in a population until some event - perhaps a sudden environmental change - causes large-scale die-off and the mutated members of the population come to the fore. The result of this is that in the fossil record it looks as if the original species suddenly died out and the new one abruptly took its place.

Most scientists these days accept PE to some extent but say that Gould overemphasised the "gradualist" nature of the mainstream theory - in fact evolution has never really been seen as that gradual.

Answer 3

Punctuated equilibrium is the idea that species just kind of coast along without much change until some big event happens in the environmental conditions. That causes sudden bursts of evolution and accumulations of new adaptations.

Gradualism is the idea that species change continuously, little bits at a time, and that evolution is a slow, almost imperceptible process.