Tim Tyler  wrote:

> John Wilkins  wrote or quoted:
> > Tim Tyler  wrote:
> > > John Wilkins  wrote or quoted:
> > > > Tim Tyler  wrote:
> 
> > > > Sorting can occur on aggregates as much as on
particles. Selection
> > > > can only occur on reproducing particles, and so if species are
> > > > subjected to selection, they must behave as particles in that
> > > > process. It is my opinion species do not ever behave as
particles in
> > > > a process unless the species is co-extensive with a
single localised
> > > > population.
> > > 
> > > In what manner are you claiming that species must behave as particles
> > > to be the subject of selection?
> > 
> > The logic of selection is that there is some logical atom that
> > correlates environmental constants with probability of reproduction.
> > Chemical selection has isomers which will replicate under fixed
> > conditions. Organismic selection correlates ecological traits with
> > probability of reproduction (and hence of the traits). Species selection
> > would require some aspect of the species itself, a property not merely
> > the aggregate of the properties of its parts, and an environment that
> > persists over the duration of many species.
> 
> That would be adopting the Gould/Vrba/Eldridge notion - that properties
> of organisms are not also properties of the species they compose.
> 
> I don't like their terminology - I think it is ill-conceived.

I do too.
> 
> > It is my view that this is logically possible, and practically
> > unrealised. What I think Gould is really discussing, and Vrba before
> > him, is the sorting of species according to the aggregate properties of
> > their members.
> > 
> > This may sound like a semantic quibble, and Larry has in the past stated
> > that he thinks it is. I think it is a matter of giving terms a solid
> > meaning and sticking with it. Which is.. err... a semantic quibble, I
> > guess.
> 
> I have no objection to giving terms solid meanings.
> 
> However I don't think it would be wise to *define* the properies of a
> species to necessarily exclude all the properties of its members.

There is a logical fallacy known as the fallacy of composition - that
the aggregate shares the properties of its parts. If I have a digit that
is 6" long, do I as the aggregate that includes that digit have the
property of being 6" long? No. It pays to consider the difference.
> 
> "Consisting of red organisms" *should* be permitted as a property
> of a species.  Forbidding it on the grounds that it is the organisms
> (and not the species) that is red would be playing a pointless
> semantic game, and - IMO - it would lead to much easily-avoidable 
> confusion.

No, there are two properties in play:

of the organisms - "is red"

of the species - "consists of red organisms"

"Is red"  "consists of red organisms"

> 
> I can see it might be useful to want to distinguish between emergent 
> properties of species, and those that they inherit in an additive
> fashion from their members - but I *don't* think the desire to make
> this distinction can justify bending the whole concept of
> "species selection" out of shape.

Don't get me started on emergence. It is, IMNSHO, a different way of
saying "we can't calculate it ahead of time", that's all. It has no
ontological implications, only epistemic ones.
> 
> *Everyone* agrees that species selection in biology should refer to
> differential reproductive success of species - i.e. on selection
> "choosing" species on the basis of differences between them.
> 
> The sole point of contention is whether things like;
> 
> * "consisting of large organisms"
> 
> ...and...
> 
> * "consisting of winged organisms";
> 
> ...should be permitted as properties of species which are eligible for
> being used to distinguish between them.

Logically, yes, they can. That is why I said above it is logically
possible. But "consisting of winged organisms" has to have an *economic*
differential value for the *species* to be selected (or any
supraorganismal entity). Otherwise the species merely inherits the
selective values of the organisms, and there is no species *selection*
going on here, just sorting.
> 
> I think they should - and it seems such a simple point that I'm rather
> surprised that the issue is under debate in the first place!
> 
> Noboby denies that the car is red, because it is *really* the individual
> paint molecules that have the redness - and the redness of the car is
> wholly a product of the redness of the paint.
> 
> If you read defenses of the idea you will see they say things like:
> 
> ``it isn't the *species* that can fly - it's the *individuals*
>   of the species who can fly''
> 
> ...but this is *entirely* a semantic game.  You can get precisely the
> reverse conclusion by simply rewording:
> 
> ``it isn't the *individuals* that consist of winged organisms -
>   it's the *species* that consitsts of winged organisms''
> 
> The *only* reason I can think of for wanting to make properties of 
> individuals and properties of species mutually exclusive would be
> if we wanted to make sure "species selection" and
"individual selection"
> were always different theories - and always made different predictions.
> 
> ...but why should anyone care about that?
> 
> What's the problem with these two theories making the same predictions
> some of the time?
> 
> Noboby quibbled when quantum theory made the same predictions as Newton's
> theory (under some circumstances) - so what exactly is the problem?
> 
> The best thing to do with the whole notion of "species sorting" is
> to cremate it as soon as possible.
> 
> The terminology is bad - not because it is esoteric - but because 
> its existence forces the term "species selection" to mean something
> different from what it intuitively and obviously *should* mean.
> 
> > > If species easily merged together then there might be little
significance
> > > to species-level selection - but it is widely accepted that they don't
> > > deviate from particulate behaviour in *that* particular respect.
> > 
> > Umm, that all depends on the nature of the organisms - gamete
> > broadcasters like plants, corals, some fishes, *do* speciate in that
> > manner. Ferns (Pteridophytes) have something like a 97% allopolyploid
> > speciation.
> > 
> > Hey, if you are right, then we should see no speciation trends in
> > Pteridophytes...
> 
> Gametes from species A fertilising species B and producing species C
> is not what I intended to refer to as "merging".  Maybe I should
> have used the term "blending".
> 
> Extensive horizontal gene transfer *would* blur the individuality of 
> species.  Such horizontal transfer may happen - but apparently not on a
> large enough scale to destroy the individuality and identity of species.

So it's just introgression you think causes problems? I'm not sure what
you are saying here. Compilospecies exist (introgressive species - do a
lit search). I think yo8u are saying they ought to show no trends.
However, that is a species pair relation, so no trends will exist by
definition.
> 
> > > IMO, species' gene pools form "particulate" blobs
in gene space.
> > > 
> > > They may be a /little/ bit smeared out in that space, but are quite
> > > particulate enough to permit selection between them to take place.
> > 
> > Can selection take place between anything that occupies a metric space
> > in virtue of that fact, or do they need to have some cohesion? I think
> > they do. Clouds have locations, but they aren't selected between.
> 
> Species' gene pools surely have "cohesion" in abundance.

*Surely*? I rather doubt the certainty there. *Some* gene pools may, but
I doubt that it is a sine qua non of gene pools.
> 
> Streams in Dawkins' river divide - but rarely rejoin.

And he is, I think, less right than he ought to be. There are a slew of
cases of "rejoining" ranging from horizontal genetic transfer through to
a number of groups in which hybridisation is common on a daily basis
(eucalypts, for example, and ferns).
> 
> They thus have distinct and separate identities.

Or the ones that don't have apparent identities while the ones that do
are ignored.
> 
> Gene land is not like a flood plain - where nobody can tell where
> one species ends and the next one begins.
> 
> Clouds have *some* coherence as well - though not as much as
> entities like species or crystals do.  They can even make
> crashing noises when they bang into each other ;-)
> 
> They are subject to differential success - depending on their
> properies.  For example, small clouds are more prone to
> evaporation than large clouds - I believe - through being
> more exposed to the sun.
> 
> Clouds do suffer from low heritability and a high mutation rate, though.

Yeah, but some of them can be very like a weasel...
-- 
John Wilkins
john_SPAM{at}wilkins.id.au   http://www.wilkins.id.au
"Men mark it when they hit, but do not mark it when they miss" 
                                               - Francis Bacon
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