Read full document


By | April 2012
Page 1 of 2
Phyletic gradualism, proposed by Charles Darwin, describes evolution as a slow steady process that organisms change and develop slowly over time. These changes happen over a short period of time and are hard to notice, often happening in small populations. These species change until there is no longer any trait of its original DNA, becoming a new species and the original species now becomes extinct. The species will continue to adapt to the new environment and biological selection pressures over the course of their history, gradually becoming new species. (International Journal, December 4 2011) While phyletic gradualism and punctuated equilibrium both explain the rate of evolutionary process, they have differences.

Punctuated equilibrium states there are long periods of no change, followed by rapid periods of change. These events happen rapidly in geological time over many years and little changes occur in that time. The periods of time are broken up by periods, and then branch into speciation called cladogenesis. From here the species are split into distinct form equally. Punctuated equilibrium has three concepts: stasis, punctuation and dominate relative frequency. Stasis refers to a long period of relatively unchanged form; punctuation is radical change over a short duration; and dominant relative frequency is the rate these events occur in a particular situation. Punctuated equilibrium was developed as an alternative to phyletic gradualism, which stresses consistent, cumulative changes to species. (Eldridge and Gould, 1972)

Punctuated equilibrium attempts to answer the major issue with the fossil record. Scientist assumed that the gaps in the fossil record would eventually be filled, leaving a somewhat complete record of the transitional forms between the various species. However, the opposite happened and the gaps became even more noticeable. Most species did not change much over time, but had occasional major changes in brief periods of time....

Rate this document

What do you think about the quality of this document?

Share this document

Let your classmates know about this document and more at