>Wesley Elseberry responded to my question whether there is any evidence for
>modern competition between species of the kind that can be a significant
>factor in evolution--evolution that is usually called "Darwinian
>evolution," although Wesley says that _that_ kind of evolution was not
>postulated by Darwin. In his response, Wesley also said:
>The ONLY thing that interests me in this thread is whether there is modern
>evidence for "natural selection" of the kind ( I take it, competition
>between species) that can account for evolution--usually called Darwinian
>evolution, but we can drop the adjective for the sake of the argument.
It is incorrect to think that competition BETWEEN DIFFERENT species would be
the major driving force behind natural selection. Theoretically, two
species occupying the same environmental niche could drive some degree of
evolution. However, the way that the natural selection model is envisioned
is that in forming new species, individuals from the SAME polymorphic
species, but in competition with each other, or found in different
environments where the selection pressures are different, will evolve into
new species. This has been seen in the modern world, albeit on a
MICROevolutionary scale.
This question gets to the problem of identifying what the unit of selection
is. Evidence suggests that selection may occur at either the level of
individuals within a population, or at the level of populations within a
species. (However, some argue that the unit of selection is the gene).
Steve
_________________________________________________________
Steven S. Clark, Ph.D . Phone: 608/263-9137
Associate Professor FAX: 608/263-4226
Dept. of Human Oncology and Email: ssclark@facstaff.wisc.edu
UW Comprehensive Cancer Center
CSC K4-432
600 Highland Ave.
Madison, WI 53792
"It is the glory of God to conceal a matter, but the glory of kings to
search out a matter." Proverbs
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