Are species real?

pierre deleporte pierre.deleporte at UNIV-RENNES1.FR
Wed Apr 12 12:42:59 CDT 2006

A 17:09 11/04/2006 -0500, Fernando Vaz-de-Mello wrote :
>interbreeding populations do exist
>monophyletic groups of populations do exist
>close resembling individuals do exist
>various levels of interbreeding isolation do exist
>assemblages of invividuals associated to a scientific binomium do exist
>etc... do exist

Yes we can talk of "existing" for "being real". There is no problem, 
provided that we distinguish different modes of "existence", either as a 
material system standing by itself out there, or as a class concept we can 
agree on in some cultural / scientific theoretical context.

- existence as a concrete material system: an interbreeding population, or 
metapopulation with various degrees of interbreeding isolation (not zero), 
could be a limit case of such a material system (although specific 
interactions between the living individuals composing such populations may 
happen to be few and far between, hence the composition and boundaries of 
this material system difficult to figure out by direct observation, because 
the system itself is quite "losely connected", if materially coherent at all);

  - conceptual existence: of course we can also conceive of a population as 
the class of all organisms sharing the properties of living at the same 
time in the same place (to be geographically delimited) and being 
potentially interbreedable (even if all individuals are never really 
"connecting" in any material way). Other classes mentioned above also fall 
into this category. We can conceive of a class of populations considered as 
sharing the property of exclusive common ancestry under some limiting 
criterion for inclusion, or class of populations showing various degrees of 
potential interbeeding abilities, of a set of individuals sharing some 
morphological similarities, or the set of individuals consensually falling 
under the same scientific naming for some reason. All these notions "exist" 
as concepts, hopefully making some sense in some context. They 
"conceptually exist" by definition because they have been conceived by some 
human beings, and can be understood by other ones, and their relevance 
(utility) in some contexts can thus profitably be debated on... provided 
that class concepts are not confused with existing material systems, which 
confusion the terms "real" or "exist" seem to convey sometimes.

>why don't simply call them by their names (and not "species" without
>defining it) and then stop discussion on its reality as a single entity?

If this is agreed on, then "naming a species" is not a question of "calling 
by its name" an existing, self-consistent material system everybody could 
unambiguously check out there, but a question of defining a class of 
individuals a useful way, for communicating in some cultural context (and 
nomenclatural rules can help avoiding ambiguity in communication).

>or are we facing a simple semantic problem droven by a nomenclatural
>(I am telling about codes) debility?

I think we are facing the problem of considering what "obvious" consistent 
material systems exist out there (not species, unless limited to one living 
specimen or one living group), and what kinds of classes of biological 
things we need to conceive of for some purposes (possibly species of this 
or that kind).

In such a vision, "just name the obvious species" is excluded as 
To answer a question of Ken Kinman : "But can one really say that the 
aardvark species is not real?", I would say: how do you know that there are 
not two 'real' species of aardwarks? Which would raise the question: what 
is your definition of "species" in general, or for aardwarks in particular? 
Just staring at some aardwarks out there will never answer such questions, 
however "obviously different" (and similar among them) aardwarks may 
intuitively seem. As noted in other posts, "being easily distinguishable" 
is not identical with "existing" (either as a consistent material system, 
or as a clearly defined and useful class concept).
"Blue things" constitute an easily distinguishable class of things (some 
parrots, motorbikes and violets...). And for a logician, the class of blue 
things can be said "natural" (all these objects share a common property). 
Just teasing a bit...


>Fernando Z. Vaz-de-Mello
>Instituto de Ecología, A.C.
>Departamento de Biodiversidad y Ecología Animal
>Km 2.5 Carretera Antigua a Coatepec, 351
>Congregación El Haya
>91070 Xalapa, Veracruz
>Tel. (+52) (228) 842 18 00 #4111
>Fax (+52) (228) 842 18 00 #4102

Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 63
Télécopie : 02 99 61 81 88

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