Paraphyly

Joseph E. Laferriere joseph at IRIS.CEAMISH.UAEM.MX
Wed Jun 18 07:59:32 CDT 1997


> Joseph Laferriere writes
> >...
> > The only time directional selection will be in effect is either
> > during periods of climatic change or if the species is invading a new
> > habitat.

On Tue, 17 Jun 1997, Richard Jensen wrote:

> This is an oversimplification of the forces of selection - directional
> selection could also occur as a result of response to herbivore pressure,
> invasion of new competitors (i.e., weeds), response to fungal or other
> parasites, etc.  In other words, there are many phenomena, in addition to
> climatic change or invading new habitats, that could lead to directional
> selection.

Joe answers,

Yes, I know this. I meant "environmental change" rather than "climatic
change." The former would include everything you list.




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