How do gradualism and punctuated equilibrium differ? How are they similar?

1 Answer
Nov 13, 2016

both gradualism and punctuated equilibrium assume natural cause and common descent of all organism. They differ in the the assumed rate and means of genetic change

Explanation:

Classic Neo Darwinism is based on gradualism or uniformtarism. The assumption is that small gradual changes could account for the tree of life starting with a "simple" one cell organism to complex modern life forms.

The fossil record does not support the concept of small gradual changes resulting in new life forms. Fossils show changes within a species resulting in new forms of the that species but not transition between types of species.

Punctuated equilibrium was a theory proposed to explain why the small changes proposed by gradualism and the Neo Darwin theory are not observed in the fossil record. The theory proposes that small isolated populations subjected to environmental stress and changes changed fairly rapidly. As the changes occurred in an isolated small area and over a relatively short time the fossils were not preserved.

The differences is that Classic Neo Darwinism says that genetic changes happen slowly and small changes. Punctuated equilibrium proposes that changes occur more rapidly, in fits and starts.

Both accept that life started from a "simple" cell and that natural selection can account for the diversity of life presently observed.