Re: What is a Species (was Re: Iris setosa)


>
>What are the criteria that plant taxonomists use to determine what is a
>species? There seems to be a major grey area in certain wild populations in
>determining what are species and what are naturally occuring hybrids. I
>guess that's what makes taxonomy fun.
>

We spend a couple of days talking about species concepts in my Evolution
course--so it's hard to boil it down here.

The dominant species concept was articulated by Mayr and is called the
Biological Species Concept--"A species is a population or group of
populations reproductively isolated from other such populations."  In other
words, members of different species should not normally interbreed
successfully, at least under natural conditions.  This concept appears to
work well for animals but is not so good with plants, where the
interbreeding of what would appear to be species is relatively common.
Based on these criteria, zoologists would, if they had their way, recognize
far fewer species of plants than do botanists.

There are other species concepts.  Many botanists seem to like the
Ecological Species Concept, in which a species is a population that
occupies a distinct niche.  There are big formal problems with this.

Some even question if the category "species" really applies to plants at
all...but I get the impression that a species in plants is what botanists
decide it is, using all relevant information.

Any botanists want to jump in on this?

Bill Shear
Department of Biology
Hampden-Sydney College
Hampden-Sydney VA 23943
(804)223-6172
FAX (804)223-6374
email<bills@hsc.edu>
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