species concepts (this is long!)

[John Grehan]

I've inserted some commentary on the species views posted by Warren:

At 01:33 AM 11/22/01 -0800, you wrote:

>There is certainly no concensus among systematists as
>to what species concept should be used.

In which case it would seem that definitions of species do not matter.

  This is not a universal reality for
>species (because of different species concepts), but it
>is not even possible for subspecies since they
>necessarily cannot be equivalent because there is no
>standard definition for them.

As show by Warren, there is no standard definition of species either!

>All workers that use
>subspecies have different working definitions of
>subspecies,

True of species as well.

>All of this means that in the
>business of taxonomy, subspecies are entirely
>subjective.

So definitions are the foundation of objectivity?

>They may be useful in summarizing
>variation, but cannot be objectively applied.

If objectivity is the slavish application of a particular definition one 
does not seem to be any better off. Tyranny of definitions.

>Workers
>who propose subspecific names should strive to reach a
>standard definition for a subspecies to remove some
>subjectivity from their decisions.

If this authoritarian dictation is to be imposed on the use of subspecies 
then proponents of species definition should be held to the same criterion.

>The species problem is big enough!  Mayden (1997)
>identified at least 22 species concepts in the
>contemporary literature.

I have not read this article, but it is likely that most if not all fall 
under the species as a class concept. I have illustrated this view below 
with a slight re-wording of the definitions provided.

>Biological Species Concept (by Mayr),
>The essence of species is reproductive isolation

>The Hennigian Species Concept (by Meier and Willmann),
>The essence of species is reproductive isolation of natural
>populations or groups of natural populations.  (I won't even pick on the 
>"natural" criterion - another can of worms).


>The Phylogenetic Species Concept (sensu Mishler and
>Theriot) by Mishler and Theriot,
>The essence of species least inclusiveness.

>The Phylogenetic Species Concept (sensu Wheeler and
>Platnick), by Wheeler and Platnick,
>The essence of species is a unique conbination of character states."
>
>  Evolutionary Species Concept (by Wiley and
>Mayden),
>The essence of a species is maintenance of identity
>
>
>There are huge differences between some of these
>species concepts, and in their application and
>consequences.

In terms of spatio-temporal independance these different definitions are 
really not all that different afterall.

>A strong proponent of any one species
>concept should be familiar with other competing
>concepts as well, to understand the strengths and
>weaknesses of them all so that their own beliefs can be
>better justified.

This seems to me a wishy washy kind of perspective.

>It seems appropriate
>to me that workers should have a defined, specific
>species concept that is applied in their research, and
>that the concept be consistently applied.

Since there is an abundance of competing species definitions that may all 
have validity perhaps species definitions are really a waste of time?

>This enables
>workers to defend each and every taxonomic decision
>they make on the grounds of their species concept.

Why bother having to defend one's taxonomic decision. If there are 
competing views and all have validity, defense seems to become irrelevant.

>Since there is no scientific definition of a subspecies
>(we only have ICZN rules dictating how to deal with
>them), there cannot be anything "non scientific" about
>how a worker treats them or what characters they use to
>differentiate them.

This seems to be a good argument as to why species do not matter anymore 
than anything else in biology and why species definitions are also not 
particularly important.


>"Evolutionary" and biogeographic
>factors are not always known with certainty, and only
>add more ad hoc hypotheses to the to the theory of a
>subspecies; making the hypothesis of a subspecies less
>testable.

The imposition of ad hoc hypotheses in defence of a theoretical position is 
a time-honored tradition in science (I include biology, chemistry, and 
physics) and it can generate progress regardless of 'testability' (which is 
not the only criterion for science).


>In the eyes of many scientific philosophers
>(as explained in works by Popper and Farris among
>others) the best scientific hypotheses are those that
>are the most testable,

This is just one philosophical view. Under this criterion witchcraft is 
science.

>those with the fewest associated
>ad hoc hypotheses (this is to say, the most
>parsimonious exalanation is the best).

Again, just a philosophical abstraction that may or may not be true. Again, 
also a good example of philosophers as the unpaid mercenaries of science.


>On Nov. 20, Ron Gatrelle Wrote:
>"Phenotypic (how critters look to people)
>subspeciation is the weakest and least significant type
>of subspecific
>delimitation."
>
>My reply:
>Again, there are no rules, or even published
>suggestions as to which characters are more useful in
>determining subspecific relationships than others.

Even if there are 'rules' (as have been invoked in species definitions), 
one is not necessarily any better off.

>To
>give meaning to the above statement, a formal
>definition of a subspecies, along with information on
>what characters should be used in the taxonomic
>analysis must be presented.

Again, why bother. As in species one may make up or accept a definition and 
be none the wiser.


>On Nov. 20, 2001, Jaska Kullberg wrote:
>"In general I feel that frigga is a good species to
>represent a holarctic
>species  as it lives abundantly and commonly in
>northern vet tundra
>thorought Europe and N.Siberia."
>
>My reply:
>This type of statement is easily justifiable in the
>eyes of the Biological Species Concept, or the
>Ecological Species Concept, for example.  There is
>nothing "wrong" with this point of view, if those
>species concepts seem reasonable and are justified by
>their proponents.

So anything goes, and out with the philosophy after all?

John Grehan


 
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