Mayr on "What is a Species"

[pierre deleporte]

At 15:46 23/04/2004 -1000, Richard Pyle wrote:

(plenty of much too nice things, and):

>1) Pierre Deleporte [...] I'm still not sure I understand why he seems to 
>regard a "population" as something fundamentally more individual-like than 
>a "subspecies" or "species"; but I suspect it will ultimately prove to be 
>an issue of semantics, like so many others in this thread).

It's both an ontological and semantic issue.

If you think of a population including dead individuals, then there is no 
difference with a subspecies or a species in this respect: one means in 
fact the class of individuals, dead or alive, sharing some property (e.g. 
being, or having being, part of the spatially and reproductively defined 
and evolving system we call "this population"). However clearly delimited 
or loosely delimited this "same population" can be in any of its successive 
states, the fact is that dead plus alive individuals can't constitute a 
"concrete cohesive whole".

Now if you consider only living members of a "same population", along a 
wide spectrum of possible situations (of spatial closeness, of internal 
biological connectedness...), you have something you can consider as a 
biological system of some kind. I think I never used "individual" for a 
population, but rather "biological system".
  A social group can even be viewed as something more biologically cohesive 
than a population in some respects: its living members may constitute a 
fairly well circumscribed and "closed" biological system, during the time 
it lasts...
( OK OK OK it changes in composition through time, and we may go on calling 
it the same group, etc... anyway the dead are the dead, the yet-to-be-born 
as well as the yet-to-come-and-join the group can't belong to the cohesive 
concrete biological system, while the not-yet-departed social partners 
shouldn't be arbitrarily ignored).

All these systems (individual, social group, population) I would call 
"biological concrete wholes" of some kind, the effective living individual 
being far more "biologically concretely cohesive" (anatomically, 
physiologically) than any social group or population of any kind (the 
"supra-organism" metaphor for the eusocial insect colony is but a metaphor).

[[Note that the scientific context is crucial for the relevance of our 
apprehension of concrete reality (social group for social studies, 
individual for physiology, social group and population for population 
genetics...). This echoes the question of the hierarchy of systems, and 
also the question of the relevance of different classifications for 
different uses.]]

Now, from the moment when you mix up dead (cells, individuals) with living 
ones, you certainly begin to deal with a class (possibly biologically 
meaningful), i.e. things you decide to group together given certain 
criteria, and you are no more talking of an individual or of a concrete 
system of spontaneously grouping individuals out there.

I think Ron Gatrelle also makes the point quite clearly in its last posts. 
Let's differentiate (at the very least) real biological systems from human 
constructs (even if scientifically relevant).
No class without a classifying brain. If there is no classifying being, 
there is nobody to infer any "connection" between the dead and the living, 
the close and the remote, and all kinds of scientific explanations...

>2) I'm not sure I fully understand Ron's insistence that the notion of
>"subspecies" holds some special meaning to be distinguished from "species";
>except that "subspecies" just happens to be the smallest class of
>individuals addressed by the ICZN Code of Nomenclature.

I fear I agree, and I fear I don't want to tease Ron any more... Besides 
"population" properly (with all the associated mess...) I perceive 
"subspecies" as a possible kind of fig leaf for apical phylogenetic 
fuzziness, but you already made this point some way...

Thanks for stimulating "babbling"
Pierre


Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 66
Télécopie : 02 99 61 81 88