Phyletic gradualism
As described by Eldredge and Gould, the essential features of phyletic gradualism are:
1. New species arise by the transformation of an ancestral population into its modified descendants.
2. The morphological transformation is even and slow.
3. The transformation involves large numbers of organisms, usually the entire ancestral population.
4. The transformation occurs over all or a large part of the ancestral species' geographic range.
The above points are sometimes mistakenly ascribed to Darwinian evolutionary theory. However, Darwin’s description of, “very slow, intermittent action of natural selection” [ Ch. 4 ] disagrees with point 2, and another passage in Darwin’s Origin of Species disagrees with points 3 and 4. (adapted from here)
Tables Mechanisms of Biological Evolution : Gene Regulation in E.coli :
Blue terms hyperlink to explanatory items. Linked items can also be found by way of the 'Links to this post' list at the base of some posts (once Blogger catches up!). Use the "back" function to return to the departure item.
Items occur within Sections. When visiting an item, the site title changes to purple – click on the title or “Home” to return to the main page. Topics are listed in the Site Map (click on arrow at top of sidebar). The site is searchable – once Blogger catches up – by way of the 'Search this blog' window at upper left.
When the number before the “Guide-Glossary” link (below each item) is greater than 0, the link provides a glossary of terms. Displayed as a pop-up when reading within a Section, or as sub-script when visiting an Item.