Subspecies, ecotypes and conservation of biodiversity

Russell Seymour R.Seymour at NHM.AC.UK
Thu Jun 12 08:06:30 CDT 1997


Some weeks ago I posted a question to this list headed "the value (or not)
of subspecies". I asked for replies off list for which I was (justifiably)
chastened by certain other list members. Their point being that this is a
'hot topic' deserving of wider discussion. The responses I received
represented both ends of a full spectrum of opinion and everything in
between! For these reasons I would like to throw open the debate to the list.

I will start by clarifying some of my own thoughts and defining my criteria
for subspecific recognition.

My interest originates from a conservation viewpoint - to maintain
biodiversity and the ecological and evolutionary processes supported by it.
Patently, new species come in to being at the population level and must have
transient 'subspecies' stages which can be identified (Note that I refer not
only to the formal taxonomic rank of subspecies but to any subspecific
structuring). Local species assemblages and regional variants then produce
unique communities. So is it valid to only conserve 'representative samples'
of species (the conservation equivalent of taxonomic 'types') when such
variation exists?

My own criteria for recognising subspecies include the following:

FIXED GENOTYPIC, PHENOTYPIC OR BEHAVIOURAL VARIATION which demonstrates
recognisable divergence and implies significant separation of intraspecific
populations with no gene flow between them. (So where can clinal variation
fit in?)

CONSTANT ENVIRONMENTALLY INDUCED VARIATION. This point illicited the
greatest response to my last mailing typically, though not exclusively,
refuting this idea. Let me clarify: As I have already stated I hold a
conservationist point of view, and conservation of whole communities rather
than individual species. My holistic perspective also recognises that
'taxonomic units' are a result not only of the genetic make up but also
environmental influences. If the environment induces a constant
morphological form this is indicative of the unique nature of that
community/environment and is surely deserving of recognition. Perhaps this
would be better described as an 'ecotype'?

This last point opens a further question: One of semantics and terminology.
Should subspecific variation be recognised by formal taxonomic ranks or
should this be left to ecologists and conservation biologists? Should we use
subspecies, ecotypes or 'evolutionary significant units' and how should they
be defined? Species concepts play a role here too: A subspecies under the
biological species concept could easily be a full phylogenetic species. Can
this be resolved?

In summary, is recognition of subspecific structure useful in taxonomy,
ecology, evolution or conservation biology? If so, how and why? If not, why?

I have tried to be brief in introducing my thoughts and questions. There are
many more facets to both sides of this argument and I hope we can discuss
these here. I look forward to a heated (but friendly) debate.

Thanks in advance

RUSS

P.S. My Masters thesis considers questions of subspecific taxonomy and its
usage, particularly with respect to conservation. Please note, however, that
I am not seeking an easy write up by writing to the list. I have strong
opinions of my own and simply want to consider and discuss other viewpoints.

P.P.S. I have posted this question to a number of lists to gauge opinion
from variety of specialties and I apologise if you receive multiple copies.
____________________________________________________________________________

RUSSELL SEYMOUR MRes.   MSc. Advanced Methods in Taxonomy and Biodiversity
THE NATURAL HISTORY MUSEUM, LONDON and IMPERIAL COLLEGE, LONDON UNIVERSITY




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