>>Macroevolution is defined by most biologists as evolution which
>>results in species-level change or higher. Because speciation
>>has been observed to happen, it is almost universally the case
>>that denial of observed phenomena doesn't happen.
>
>That is a new use of the term "macroevolution". I have seen it used to
>refer to everything except speciation. This perversion of the usual use of
>the word is designed to attempt to force every change into macroevolution
>and thus remove one of the strongest objections to biological
>macroevolution: it has never been observed.
The definition given by Wesley is the one I have most often encountered
within the paleontological/evolutionary literature. There are other
definitions to be sure, but speciation remains the one sure demarcation
line (if one exists). The origin of higher taxa are ultimately speciation
events, whether or not one wishes to employ macromutations. The mechanisms
of speciation are still not well understood, and much disagreement exists.
Establishing and maintaining reproductive isolation is not a simple
process.
You may want to refer to my new web article now posted on the ASA webpage -
"Taxonomy, transitional forms, and the fossil record." It discusses some
of these issues.
Keith
Keith B. Miller
Department of Geology
Kansas State University
Manhattan, KS 66506
kbmill@ksu.ksu.edu
http://www-personal.ksu.edu/~kbmill/