Re: NANFA-- subspecies (was fantail darters)

Bruce Stallsmith (
Sun, 23 Jan 2000 12:50:13 EST

The truth of the matter is that there are various species concepts used and
debated, depending on the organisms in question. The Evolutionary Species
Concept that Dave describes was developed largely out of the development of
cladism as an organizing structure (and philosophy, as the others) for
systematics. Cladistics is based on drawing cladograms, branching structures
representing living groups organized on the basis of shared, derived
characteristics. The more in common by your measurements, the closer they
are in sharing recent common ancestry. (This is my summary, speaking as one
who is not a convert.) This has the advantage of being a very structured
order of rules, especially the concentration on establishing degrees of
relatedness. It can be criticized for assuming too much about speciation
events in the past within its methodology, and doing it in a very rigid,
ideological fashion. This leads to an inherent assumption of evolutionary
tendencies and historical fates, which I have a problem with. Speciation and
evolutionary events in general are not predictable events; there is a large
(but indeterminate) element of chance in these processes. There may be long
term selection pressures on a given group, such as developing a stronger
swimming style or developing improved vision. But these pressures can ebb
and flow, and maybe even stop completely.

Where does this put me? I'm not a working systematist, like Dave is. As a
working organismal biologist I still use Ernst Mayr's Biological Species
Concept as my starting point -- "Species are groups of interbreeding natural
populations that are reproductively isolated from other such groups." In
practice this means that I would consider ecological and behavioral
information as well as looking at more purely physical traits in terms of
defining species.

This may all seem silly on some level. But it's a very real issue in
biology, because it really defines how you view what you're working with.
This debate has been really nasty on occasion within biology, especially in
the early 70s when cladism became big. Methodologically I understand the
appeal of the ESC and cladistics in general. I just don't think it answers
all the questions it claims to. Your mileage may vary, of course...

--Bruce Stallsmith
Huntsville, AL
"Is biology a science or a philosophy, or maybe both?"

>I might add that Dave covers this pretty well, and that the old systems
>are still hanging on. I myself even use the term Sub-species without
>thinking about it although I know it's now falling out of favor. A lot of
>guys like Joe Collins have made some good enemies by adopting the new
>concept. It seems science accepts new ideas slowly too. ;)
>On Sat, 22 Jan 2000, Dave Neely wrote:
> > Richard,
> >
> > >>Besides, the category "subspecies" is a nonsensical term anyway, >>and
> > >>no place in a classification of diversity.

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