Species selection



T

Tim Tyler

Guest
(Probably) my last Devil's Chaplain comments concern Dawkins treatment of species selection - on
pages 265-266.

He describes the adaptedness of organisms to their environment - and attributes the "goodness of
fit" it produces to natural selection.

Then he goes on to describe the ecosystems. He says they exhibit a similar "goodness of fit" - with
different species playing the roles of different organs. Some capture energy from the sun, others
consume the sun worshipers. Others break down their dead bodies and recycle the wastes. It all seems
purposeful, directed and ordered - much like the organs in the body of an organism.

Then Dawkins writes:

``The temptation is to think that this second illusion is crafted by the
same kind of process as the first: by a version of Darwinian selection
but at a higher level. [...] I believe that this theory is false.''

He goes on to write:

``As Adam Smith understood long ago, an illusion of harmony and real efficiency will emerge in an
economy dominated by self-interest at a lower level. Well balanced ecosystem is an economy - not an
adaptation.''

I take Dawkins' point - but he goes too far for me.

He gives species selection no quarter. He does not point out that species selection gets the final
word in terms of what lives or dies. He doesn't even discuss relative reproductive rates. He just
*totally* rejects the whole theory of species-level selection as "erroneous".

I think almost everyone agrees that an ecosystem is first and foremost an economy - and that *most*
of its features can be explained well in those terms. However I would not like to state that none of
it is best described in terms of species-level differential reproduction and selection.

The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
selection properly at all.

If not, that isn't good news - IMO.

Species *do* reproduce, vary and exhibit differential reproductive success - albeit at a rather slow
rate of knots - and so are practically bound to evolve by natural selection.

The idea that gene-level selection totally and precisely undoes all the effects of species selection
is absurd. Rather organisms are the result of a tug of war between these forces - with neither one
completely dominant.

Dawkins has written enough about group-level and individual-level selection in the past - and with
most of it sensible stuff (if sometimes a bit strong).

I would hate to have to form the opinion that - on this point - he doesn't really know what he is
talking about.

This section was a forward to an ecology book - perhaps one can still hope that he just dumbed
things down a bit far.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove lock to reply.
 
(Probably) my last Devil's Chaplain comments concern Dawkins treatment of species selection - on
pages 265-266.

He describes the adaptedness of organisms to their environment - and attributes the "goodness of
fit" it produces to natural selection. Then he goes on to describe the ecosystems. He says they
exhibit a similar "goodness of fit" - with different species playing the roles of different organs.
Some capture energy from the sun, others consume the sun worshipers. Others break down their dead
bodies and recycle the wastes. It all seems purposeful, directed and ordered - much like the organs
in the body of an organism.

Response: I don't see a "similar goodness of fit" in the adaptiveness of organisms to their
environment to ecosystems. Interdependecies among organisms as reflected by producers, consumers and
decomposers is a different process based on energy recycling..not natural selection. I also contest
the idea that adaptiveness of organisms to their environment necessarily produces a "goodness of
fit" due to natural selection. As far as humans are concerned I don't think we have adapted to our
current environment. If one accepts that premise where is the "goodness of fit" due to natural
selection?

Then Dawkins writes: ``The temptation is to think that this second illusion is crafted by the same
kind of process as the first: by a version of Darwinian selection but at a higher level. [...] I
believe that this theory is false.´´

Response: There are many "illusions" floating around. If Dawkins doesn't think ecosystems are
governed by the higher processes of natural selection than why does he make an analogy between the
"goodness of fit" between natural selection and the "goodness of fit" of ecosystems?

He goes on to write: ``As Adam Smith understood long ago, an illusion of harmony and real efficiency
will emerge in an economy dominated by self-interest at a lower level. Well balanced ecosystem is an
economy - not an adaptation.´´ Response: Geez, I hate invoking the economy of Adam Smith with the
economy of an ecosystem. I don't think the two are the same. I don't think an ecosystem in an
economy in the Adam Smith sense or an individual adaptation. Collectively speaking, however, it
represents the numerous adaptations which make up an ecosystem. And here it is indeed appropriate to
refer to the illusion of harmony and real efficiency. One could say human society has emerged in an
economy dominated by self-interest at a lower level. What has been the effect of the ecosystem? Has
it been "well balanced"? Greenhouse effect, acid rain, industrial emissions, logging, etc.

I take Dawkins' point - but he goes too far for me. He gives species selection no quarter. He does
not point out that species selection gets the final word in terms of what lives or dies. He doesn't
even discuss relative reproductive rates. He just *totally* rejects the whole theory of species-
level selection as "erroneous". I think almost everyone agrees that an ecosystem is first and
foremost an economy - and that *most* of its features can be explained well in those terms. However
I would not like to state that none of it is best described in terms of species-level differential
reproduction and selection.

Response: What does an ecosystem have to do with species-level differential reproduction and
selection? An ecosystem is an array or organisms and their physical environment, all interacting by
a flow of energy and a cycling of materials. Irrespective of species-level differential reproduction
and selection that same flow of energy and cycling of materials will occur. I would describe an
ecosystem as an economy in the sense of being a mode of operation of something i.e. the flow of
energy and cycling of materials. In what sense do you think of an ecosystem as an "economy" and how
does that relate to species-level differential reproduction and selection?

The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
selection properly at all. If not, that isn't good news - IMO. Species *do* reproduce, vary and
exhibit differential reproductive success - albeit at a rather slow rate of knots - and so are
practically bound to evolve by natural selection.

Response: Interestingly, many species due to human activity have become extinct and will become
extinct. Is this due to natural selection? If so, is this something we should be concerned about?
Just out of curiousity do you regard **** Sapiens as consisting of several "species"? This is a non-
seqitor I know but certainly the differential reproductive success of various "sub-species" of ****
Sapien varies and is bound to evolve by natural selection or other means.

The idea that gene-level selection totally and precisely undoes all the effects of species selection
is absurd. Rather organisms are the result of a tug of war between these forces - with neither one
completely dominant.

Response: Yes, you say that but your leaning is apparent when you state, "He does not point out that
species selection gets the final word in terms of what lives or dies." It appears you see species
selection acting more than gene selection..or you see "both" operating in tandem within one species.
My own view is complex. I think natural selection operates on all species but in the case of humans
I think it has been weakened. Does natural selection operate on the gene level or the species level?
Here is where the concept of group selection springs up. To the best of my knowledge Darwin never
provided a theory of group selection but a theory of natural selection and this didn't include group
selection. Natural selection defined is the microevolutionary process of the outcome of differences
in survival and reproduction among "individuals" that vary in details of heritable traits. Over
generations, it typically leads to increased fitness.

Microevolution describes any change in allele frequencies resulting from mutation, genetic drift,
gene flow, natural selection or some combination of these. Needless to say these processes take time
to produce changes. Considering the length of time it does what seems more likely: species selection
or gene selection?

Dawkins has written enough about group-level and individual-level selection in the past - and with
most of it sensible stuff (if sometimes a bit strong). I would hate to have to form the opinion that
- on this point - he doesn't really know what he is talking about. This section was a forward to an
ecology book - perhaps one can still hope that he just dumbed things down a bit far.
--
__________
  |im |yler http://timtyler.org/ [email protected] Remove lock to
reply.
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> (Probably) my last Devil's Chaplain comments concern Dawkins treatment of species selection - on
> pages 265-266.
>

stimulating little book isn't it?

> He describes the adaptedness of organisms to their environment - and attributes the "goodness of
> fit" it produces to natural selection.
>
> Then he goes on to describe the ecosystems. He says they exhibit a similar "goodness of fit" -
> with different species playing the roles of different organs. Some capture energy from the sun,
> others consume the sun worshipers. Others break down their dead bodies and recycle the wastes. It
> all seems purposeful, directed and ordered - much like the organs in the body of an organism.
>
> Then Dawkins writes:
>
> ``The temptation is to think that this second illusion is crafted by the
> same kind of process as the first: by a version of Darwinian selection
> but at a higher level. [...] I believe that this theory is false.''
>
> He goes on to write:
>
> ``As Adam Smith understood long ago, an illusion of harmony and real efficiency will emerge in an
> economy dominated by self-interest at a lower level. Well balanced ecosystem is an economy - not
> an adaptation.''
>
> I take Dawkins' point - but he goes too far for me.
>
> He gives species selection no quarter. He does not point out that species selection gets the final
> word in terms of what lives or dies. He doesn't even discuss relative reproductive rates. He just
> *totally* rejects the whole theory of species-level selection as "erroneous".
>
> I think almost everyone agrees that an ecosystem is first and foremost an economy - and that
> *most* of its features can be explained well in those terms. However I would not like to state
> that none of it is best described in terms of species-level differential reproduction and
> selection.
>
> The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
> selection properly at all.
>
> If not, that isn't good news - IMO.
>

i think his whole rejection of the idea is that he doesn't see higher order groups/individuals as
being 'replicators'. I mean, he explicitly looks at whole organisms as 'vehicles' for the
replicators.

> Species *do* reproduce, vary and exhibit differential reproductive success - albeit at a rather
> slow rate of knots - and so are practically bound to evolve by natural selection.
>

i am curious as to whether nor not he agrees with this. It seems he thinks its all an
'epiphenomenon' of action at the genetic level anyways, and thus not 'real'. if he does agree that
species at least -can- act as replicating individuals, and in an 'emergent' way (ie a property of
the species not attributable to the genes) i suspect that he thinks the frequency an/or strenght of
this sort of species selection is simply overpowered by gene level selection. At least thats my
reading based on part of gould's defense of mutliple levels of selection (re:TSOET)

> The idea that gene-level selection totally and precisely undoes all the effects of species
> selection is absurd. Rather organisms are the result of a tug of war between these forces - with
> neither one completely dominant.
>
> Dawkins has written enough about group-level and individual-level selection in the past - and with
> most of it sensible stuff (if sometimes a bit strong).
>
> I would hate to have to form the opinion that - on this point - he doesn't really know what he is
> talking about.
>
> This section was a forward to an ecology book - perhaps one can still hope that he just dumbed
> things down a bit far.

probably not the best place to look for specific answers. i mean a text book, not just an
introduction to one. [/smirk]
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> (Probably) my last Devil's Chaplain comments concern Dawkins treatment of species selection - on
> pages 265-266.
>
> He describes the adaptedness of organisms to their environment - and attributes the "goodness of
> fit" it produces to natural selection.
>
> Then he goes on to describe the ecosystems. He says they exhibit a similar "goodness of fit" -
> with different species playing the roles of different organs. Some capture energy from the sun,
> others consume the sun worshipers. Others break down their dead bodies and recycle the wastes. It
> all seems purposeful, directed and ordered - much like the organs in the body of an organism.
>
> Then Dawkins writes:
>
> ``The temptation is to think that this second illusion is crafted by the
> same kind of process as the first: by a version of Darwinian selection
> but at a higher level. [...] I believe that this theory is false.''
>
> He goes on to write:
>
> ``As Adam Smith understood long ago, an illusion of harmony and real efficiency will emerge in an
> economy dominated by self-interest at a lower level. Well balanced ecosystem is an economy - not
> an adaptation.''
>
> I take Dawkins' point - but he goes too far for me.
>
> He gives species selection no quarter. He does not point out that species selection gets the final
> word in terms of what lives or dies. He doesn't even discuss relative reproductive rates. He just
> *totally* rejects the whole theory of species-level selection as "erroneous".
>

I haven't read The Devil's Chaplain, but I've read most of Dawkins's other books. As far as I can
remember, I think his view is that you don't _need_ to adopt a species level perspective to explain
any traits of living organisms and that's why he rejects explanations in those terms. It's an issue
of parsimony. You could perhaps come up with a species level account of a certain set of phenomena,
but it wouldn't add anything to what a gene level account already provides. In other cases, a
species level account may also make incorrect predictions, which is a more obvious reason to reject
it. I agree with him on this (assuming I'm representing his view accurately), but I have to say I
don't really understand the arguments that some people on this newsgroup have made for group/species
selection, so perhaps I could be persuaded to change my mind.

> I think almost everyone agrees that an ecosystem is first and foremost an economy - and that
> *most* of its features can be explained well in those terms. However I would not like to state
> that none of it is best described in terms of species-level differential reproduction and
> selection.
>
> The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
> selection properly at all.
>
> If not, that isn't good news - IMO.
>
> Species *do* reproduce, vary and exhibit differential reproductive success - albeit at a rather
> slow rate of knots - and so are practically bound to evolve by natural selection.
>

You could perhaps formulate a coherent theory of species selection, but would it explain anything
that the gene centred version doesn't?

> The idea that gene-level selection totally and precisely undoes all the effects of species
> selection is absurd.

I don't know what you mean by 'undoes'.

> Rather organisms are the result of a tug of war between these forces - with neither one completely
> dominant.

I don't know if viewing them as competing forces is really appropriate. Assuming a coherent theory
of species selection can be formulated, the process of species selection would, by definition,
operate at a different level to gene selection so wouldn't necessarily act as an opposing force. By
analogy, there are laws that apply to the motion of subatomic particles and laws that apply to the
motion of objects at everyday scales, but we wouldn't want to say that any particular motion that we
observe is the result of competition between these different sets of laws.

[snip]

H.

---
Like-minds don't notice shared mistakes. Talk to someone else.
 
Tim Tyler <[email protected]> wrote or quoted:

> I would hate to have to form the opinion that - on this point - he doesn't really know what he is
> talking about.
>
> This section was a forward to an ecology book - perhaps one can still hope that he just dumbed
> things down a bit far.

He spells out his views in more detail on p.105-108 of TEP.

He quotes Williams about how maybe horses within a line were evolving smaller size - while species
level selection between lines favoured larger sizes.

He says:

``I do not find it hard to believe that [increase of horses size - as above] are due to species
selection, in the sense of this passage from Williams, which I think is the same as Eldridge and
Gould's sense. As I think all authors would agree this is a very different matter from accepting
group selection as an explanation for individual self-sacrifice - adaptations for the good of the
species.''

I identify this as a bit of a muddled passage :-|

IMO, there's no significant qualitative difference between there being a trend towards big horses,
and there being a trend towards [say] swimming out to distant islands.

[this is my suggested example of something that might help the species reproduce - at the expense of
average individual reproductive output].

Both could involve simply turning some developmental knob. In once case, size. In the other,
curiousity.

Maybe Dawkins doesn't class something like "propensity to swim out to islands" as complex enough to
qualify as an adaptation - but there are plenty who would - including me.

Further down, Dawkins says:

``Again, it may be just a limitation of my imagination - but while I can easily see species
selection shaping a simple size trend [...] I cannot see such slow replicator elimination putting
together a suite of adaptations - such as those of whales to aquatic life.''
- p.106

If Dawkins looks, I reckon the proposed adaptations species selection is credited with aren't much
like that.

Among the list are things like a propensity to polyploidity, senescence, small size (due to
meterorite impacts) - and gentials that are close fits for one another - and tend to easily mutate
into incompatible variants.

That includes some stuff that individual selection might well let slip by
- but that species selection would be intensely interested in.

Dawkins is moderately convincing when claiming that e.g. eyes were not influenced much by species
selection.

In other cases, his case against species selection is weaker, and - IMO - he offers no convincing
argument for ruling it out completely.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove lock to reply.
 
Huck Turner <[email protected]> wrote or quoted:
> Tim Tyler <[email protected]> wrote in message news:<[email protected]>...

> I haven't read The Devil's Chaplain, but I've read most of Dawkins's other books. As far as I can
> remember, I think his view is that you don't _need_ to adopt a species level perspective to
> explain any traits of living organisms and that's why he rejects explanations in those terms.

The premise is likely to be incorrect, though.

> It's an issue of parsimony. You could perhaps come up with a species level account of a certain
> set of phenomena, but it wouldn't add anything to what a gene level account already provides.

No, no. The whole point of species level selection is that it predicts *different* adaptations.

As Richard puts it:

``[...] this really matters. Adaptations for the good of a group will look quite different from
adaptations for the good of an individual.''

> In other cases, a species level account may also make incorrect predictions, which is a more
> obvious reason to reject it.

[...]

Should it do that.

> I agree with him on this (assuming I'm representing his view accurately), but I have to say I
> don't really understand the arguments that some people on this newsgroup have made for
> group/species selection, so perhaps I could be persuaded to change my mind.

IMO, the case for species selection/group selection was put very well in Mark Ridley's *fat
textbook*, evolution. A useful read on the subject, anyway.

Both phenomena exist. The remaining theoretical question is not over their *existence*, it is over
their *strength* - compared to selection on lower levels.

> You could perhaps formulate a coherent theory of species selection, but would it explain anything
> that the gene centred version doesn't?

That's the whole point of it, yes. Different theory, different predictions.

> > The idea that gene-level selection totally and precisely undoes all the effects of species
> > selection is absurd.
>
> I don't know what you mean by 'undoes'.

E.g. if species selects for short lifespan - but individual level selection favours long lifespan,
then it is possible in theory for individual level selection to destroy the variation on which
species selection might work between each speciation event.

> > Rather organisms are the result of a tug of war between these forces
> > - with neither one completely dominant.
>
> I don't know if viewing them as competing forces is really appropriate.

Surely it is - if they favours different adaptations.

> Assuming a coherent theory of species selection can be formulated, the process of species
> selection would, by definition, operate at a different level to gene selection so wouldn't
> necessarily act as an opposing force.

Not *necessarily*, no. Very often, though.

> By analogy, there are laws that apply to the motion of subatomic particles and laws that apply to
> the motion of objects at everyday scales, but we wouldn't want to say that any particular motion
> that we observe is the result of competition between these different sets of laws.

IMO, this is a nitpick ;-)

I said two different forces would compete in organisms, and you are pointing out the possiblity of
them pointing in *exactly* the same direction, or one of the forces being zero, or them pulling on
bits of the organism which (hypothetically) are not connected.

Yes, OK - maybe /sometimes/. Those are the less interesting cases ;-)
--
__________
|im |yler http://timtyler.org/ [email protected] Remove lock to reply.
 
[email protected] (Huck Turner) wrote

> I haven't read The Devil's Chaplain, but I've read most of Dawkins's other books. As far as I can
> remember, I think his view is that you don't _need_ to adopt a species level perspective to
> explain any traits of living organisms and that's why he rejects explanations in those terms.

The perspective one choses is completely arbitrary. There is no rule or law that tells us that one
perspective is better than another. Selection is not a level/unit specific process.

It's an issue of parsimony.

Parsimony is applicable to hypotheses, not assumptions or unit.

You could perhaps come up
> with a species level account of a certain set of phenomena, but it wouldn't add anything

It would add a different perspective.

to what a gene level account already provides.
> In other cases, a species level account may also make incorrect predictions, which is a more
> obvious reason to reject it.

Incorrect predictions are possible regarless of the perspective chosen.

I agree with
> him on this (assuming I'm representing his view accurately), but I have to say I don't really
> understand the arguments that some people on this newsgroup have made for group/species selection,
> so perhaps I could be persuaded to change my mind.

Selection doesn't happen on/to levels. It happens to biological phenomena in its entirety.

>
>
> > I think almost everyone agrees that an ecosystem is first and foremost an economy - and that
> > *most* of its features can be explained well in those terms. However I would not like to state
> > that none of it is best described in terms of species-level differential reproduction and
> > selection.
> >
> > The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
> > selection properly at all.
> >
> > If not, that isn't good news - IMO.

I agree.

> >
> > Species *do* reproduce, vary and exhibit differential reproductive success - albeit at a rather
> > slow rate of knots - and so are practically bound to evolve by natural selection.
> >
>
> You could perhaps formulate a coherent theory of species selection, but would it explain anything
> that the gene centred version doesn't?
>
>
> > The idea that gene-level selection totally and precisely undoes all the effects of species
> > selection is absurd.
>
> I don't know what you mean by 'undoes'.
>
>
> > Rather organisms are the result of a tug of war between these forces - with neither one
> > completely dominant.
>
> I don't know if viewing them as competing forces is really appropriate.

I agree. They aren't competing forces.

Assuming a coherent theory of species selection can be
> formulated,

Not necessary. The theory is no different.

the process of species selection would, by definition,
> operate at a different level to gene selection so wouldn't necessarily act as an opposing force.
> By analogy, there are laws that apply to the motion of subatomic particles and laws that apply to
> the motion of objects at everyday scales, but we wouldn't want to say that any particular motion
> that we observe is the result of competition between these different sets of laws.
>
>
> [snip]
>
>
> H.
>
> ---
> Like-minds don't notice shared mistakes. Talk to someone else.
 
[email protected] (Jim McGinn) wrote in message news:<[email protected]>...
> [email protected] (Huck Turner) wrote
>
> > I haven't read The Devil's Chaplain, but I've read most of Dawkins's other books. As far as I
> > can remember, I think his view is that you don't _need_ to adopt a species level perspective to
> > explain any traits of living organisms and that's why he rejects explanations in those terms.
>
> The perspective one choses is completely arbitrary. There is no rule or law that tells us that one
> perspective is better than another.

We can choose to follow some pretty useful rules in evaluating scientific theories. The most obvious
rule we follow is that we prefer theories that make accurate predictions to ones that don't. Less
obvious, but also familiar is the rule that where two theories make the same predictions (i.e., are
notational variants of the same theory) we tend to adopt the simpler variant. We also prefer
theories that are more general, explaining a greater variety of phenomena, etc.

> Selection is not a level/unit specific process.
>

For scientists to be able to make precise predictions from a theory of selection, the theory has to
be precisely formulated. To this end, it would be extremely desirable to be able to define precisely
what is and what isn't selected.

>
> It's an issue of parsimony.
>
> Parsimony is applicable to hypotheses, not assumptions or unit.
>

But assumptions are just naked hypotheses, and just like other kinds of hypotheses, gain legitimacy
when observations or experiments turn out to be consistent with the theory.

As for the unit issue, if there is a choice between two theories, one that entertains the notion of
selection at the species level _only_ and another that entertains the notion of selection at the
gene level _only_, then yes, they're equally parsimonious, but the situation is not like that. Group
selectionists believe that there are processes acting at the level of groups, not that group
selection can account for everything that gene selection accounts for. The question being asked is
whether we need a theory that combines gene and group level selection, or whether it is sufficient
to have one that deals with gene level selection only.

> You could perhaps come up
> > with a species level account of a certain set of phenomena, but it wouldn't add anything
>
> It would add a different perspective.
>

Yes, fine, but perhaps the only kind of consistent group level account would be one that doesn't
make any predictions that don't already follow from a gene level account. A theory like this might
be useful, but wouldn't be necessary.

> to what a gene level account already provides.
> > In other cases, a species level account may also make incorrect predictions, which is a more
> > obvious reason to reject it.
>
> Incorrect predictions are possible regarless of the perspective chosen.
>

Yes of course this applies to both accounts. I was trying to distinguish between two
conceivable kinds of objections that Dawkins may have to group selection so as not to confuse
one with the other.

> I agree with
> > him on this (assuming I'm representing his view accurately), but I have to say I don't really
> > understand the arguments that some people on this newsgroup have made for group/species
> > selection, so perhaps I could be persuaded to change my mind.
>
> Selection doesn't happen on/to levels. It happens to biological phenomena in its entirety.
>

This definition of selection is too vague to be useful, IMO.

[snip stuff we mostly agree on]

H.

---
Like-minds don't notice shared mistakes. Talk to someone else.
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> Huck Turner <[email protected]> wrote or quoted:
> > Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
>
> > I haven't read The Devil's Chaplain, but I've read most of Dawkins's other books. As far as I
> > can remember, I think his view is that you don't _need_ to adopt a species level perspective to
> > explain any traits of living organisms and that's why he rejects explanations in those terms.
>
> The premise is likely to be incorrect, though.
>
> > It's an issue of parsimony. You could perhaps come up with a species level account of a certain
> > set of phenomena, but it wouldn't add anything to what a gene level account already provides.
>
> No, no. The whole point of species level selection is that it predicts *different* adaptations.

Okay, so the specific account of species level selection that you have in mind makes different
predictions, so if Dawkins rejects it, he must see it as "erroneous". I was pointing out that there
are also reasons that he may reject other conceivable species level accounts even if he believes
they are correct. See below.

>
> As Richard puts it:
>
> ``[...] this really matters. Adaptations for the good of a group will look quite different from
> adaptations for the good of an individual.''
>

I don't see why this would _always_ be the case.

> > In other cases, a species level account may also make incorrect predictions, which is a more
> > obvious reason to reject it.
>
> [...]
>
> Should it do that.
>

No, I'm just pointing out that there are two distinct reasons that could be offered for rejecting a
species level account (incorrect vs. correct but unnecessary). This means that it is possible that a
person could agree with your statement that "Species *do* reproduce, vary and exhibit differential
reproductive success - albeit at a rather slow rate of knots - and so are practically bound to
evolve by natural selection" and yet still reject species level selection as superfluous.

> > I agree with him on this (assuming I'm representing his view accurately), but I have to say I
> > don't really understand the arguments that some people on this newsgroup have made for
> > group/species selection, so perhaps I could be persuaded to change my mind.
>
> IMO, the case for species selection/group selection was put very well in Mark Ridley's *fat
> textbook*, evolution. A useful read on the subject, anyway.
>

Okay, I'll put that on my reading list.

> Both phenomena exist. The remaining theoretical question is not over their *existence*, it is over
> their *strength* - compared to selection on lower levels.
>

I'm not sure how anyone could go about answering this question. How would you measure strength in
general as opposed to in specific circumstances? Is it not conceivable that in some circumstances
the species level 'force' is stronger than the gene level 'force' while in other circumstances the
reverse is true?

> > You could perhaps formulate a coherent theory of species selection, but would it explain
> > anything that the gene centred version doesn't?
>
> That's the whole point of it, yes. Different theory, different predictions.
>
> > > The idea that gene-level selection totally and precisely undoes all the effects of species
> > > selection is absurd.
> >
> > I don't know what you mean by 'undoes'.
>
> E.g. if species selects for short lifespan - but individual level selection favours long lifespan,
> then it is possible in theory for individual level selection to destroy the variation on
> which species selection might work between each speciation event.
>

Okay, I see what you're saying in outline here, but perhaps it would be easier with a real example.

> > > Rather organisms are the result of a tug of war between these forces
> > > - with neither one completely dominant.
> >
> > I don't know if viewing them as competing forces is really appropriate.
>
> Surely it is - if they favours different adaptations.
>
> > Assuming a coherent theory of species selection can be formulated, the process of species
> > selection would, by definition, operate at a different level to gene selection so wouldn't
> > necessarily act as an opposing force.
>
> Not *necessarily*, no. Very often, though.
>
> > By analogy, there are laws that apply to the motion of subatomic particles and laws that apply
> > to the motion of objects at everyday scales, but we wouldn't want to say that any particular
> > motion that we observe is the result of competition between these different sets of laws.
>
> IMO, this is a nitpick ;-)
>
> I said two different forces would compete in organisms, and you are pointing out the possiblity of
> them pointing in *exactly* the same direction, or one of the forces being zero, or them pulling on
> bits of the organism which (hypothetically) are not connected.
[snip]

My point was a little more subtle. I was suggesting the possibility that, at least in some cases,
rather than there being two forces pointing in the same direction, one force actually _is_ the other
force at a different level of description. Given that a group is made up of individuals, you can't
talk about a group being selected without implying that all of its individuals (and their genes)
were also selected. You can choose to describe this situation at this or that level, but the
descriptions are of the same selection event, not separate ones.

The only sense my feeble mind can make of the idea of opposing forces of selection is the case where
there are two opposing forces at the same level. Perhaps in some cases where there are opposing
forces at the level of the gene (call them A and B), one of these forces (say A) will also have an
equivalent description at the group or species level in which case you might sensibly speak of
competition between A at the group/species level and B at the gene level, but this would only make
sense in terms of one of those unnecessary group selection accounts that don't make any additional
predictions beyond the gene level account, and you've already made it quite clear that you had
something more substantial in mind.

H.

---
Like-minds don't notice shared mistakes. Talk to someone else.
 
Huck Turner <[email protected]> wrote or quoted:
> Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> > Huck Turner <[email protected]> wrote or quoted:
> > > Tim Tyler <[email protected]> wrote in message news:<[email protected]>...

> > As Richard puts it:
> >
> > ``[...] this really matters. Adaptations for the good of a group will look quite different from
> > adaptations for the good of an individual.''
>
> I don't see why this would _always_ be the case.

It would not be true in every instance. *Sometimes* what's good at one level is good at other ones.
That may be a common state of affairs - but having two theories that predict much the same thing is
not the interesting case.

> [...] I'm just pointing out that there are two distinct reasons that could be offered for
> rejecting a species level account (incorrect vs. correct but unnecessary). This means that it is
> possible that a person could agree with your statement that "Species *do* reproduce, vary and
> exhibit differential reproductive success - albeit at a rather slow rate of knots - and so are
> practically bound to evolve by natural selection" and yet still reject species level selection as
> superfluous.

In the case where gene-level selection and species level selection make /exactly/ the same
predictions, then having two theories would be unnecessary. However - IMO - that would be a
fantistic, amazingly-unlikly state - which we don't need to think twice about.

> > Both phenomena exist. The remaining theoretical question is not over their *existence*, it is
> > over their *strength* - compared to selection on lower levels.
>
> I'm not sure how anyone could go about answering this question. How would you measure strength in
> general as opposed to in specific circumstances?

You probably wouldn't.

> Is it not conceivable that in some circumstances the species level 'force' is stronger than the
> gene level 'force' while in other circumstances the reverse is true?

Yes, certainly.

> The only sense my feeble mind can make of the idea of opposing forces of selection is the case
> where there are two opposing forces at the same level. [...]

Species-level selection should act to make populations more likely to speciate.

For example:

* Members of a population should have genitalia that quickly become incompatible with those of their
host population if they are isolated from it;

* They should enjoy (and be well adapted to) living on islands - since islands are where many new
species are born;

* They should be prone to changes in ploidity;

...and so on.

These may not be the same traits that best serve individual reproduction.

Indeed the traits the would best serve species reproduction may positively /hinder/ individual level
reproduction. Genitals that are verging on mechanical incompatibility with other members of your
species might well make isolated popualitons more likely to speciate - but they might also make it
more difficult to get a date.

Forces on the different levels can pull in different directions - and favour different adaptations.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove lock to reply.
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> (Probably) my last Devil's Chaplain comments concern Dawkins treatment of species selection - on
> pages 265-266.
>
> He describes the adaptedness of organisms to their environment - and attributes the "goodness of
> fit" it produces to natural selection.
>
> Then he goes on to describe the ecosystems. He says they exhibit a similar "goodness of fit" -
> with different species playing the roles of different organs. Some capture energy from the sun,
> others consume the sun worshipers. Others break down their dead bodies and recycle the wastes. It
> all seems purposeful, directed and ordered - much like the organs in the body of an organism.
>
> Then Dawkins writes:
>
> ``The temptation is to think that this second illusion is crafted by the
> same kind of process as the first: by a version of Darwinian selection
> but at a higher level. [...] I believe that this theory is false.''
>
> He goes on to write:
>
> ``As Adam Smith understood long ago, an illusion of harmony and real efficiency will emerge in an
> economy dominated by self-interest at a lower level. Well balanced ecosystem is an economy - not
> an adaptation.''
>
> I take Dawkins' point - but he goes too far for me.
>
> He gives species selection no quarter. He does not point out that species selection gets the final
> word in terms of what lives or dies. He doesn't even discuss relative reproductive rates. He just
> *totally* rejects the whole theory of species-level selection as "erroneous".
>
> I think almost everyone agrees that an ecosystem is first and foremost an economy - and that
> *most* of its features can be explained well in those terms. However I would not like to state
> that none of it is best described in terms of species-level differential reproduction and
> selection.
>
> The whole passage makes me wonder whether Dawkins appreciates the possibilty of species-level
> selection properly at all.
>
> If not, that isn't good news - IMO.
>
> Species *do* reproduce, vary and exhibit differential reproductive success - albeit at a rather
> slow rate of knots - and so are practically bound to evolve by natural selection.
>
> The idea that gene-level selection totally and precisely undoes all the effects of species
> selection is absurd. Rather organisms are the result of a tug of war between these forces - with
> neither one completely dominant.
>
> Dawkins has written enough about group-level and individual-level selection in the past - and with
> most of it sensible stuff (if sometimes a bit strong).
>
> I would hate to have to form the opinion that - on this point - he doesn't really know what he is
> talking about.
>
> This section was a forward to an ecology book - perhaps one can still hope that he just dumbed
> things down a bit far.

My take on species selection:

1. Species selection is different in concept and mechanism from Price-style group selection. Price's
covariance formula seems to be much like Hamilton's rule - it simply notices that some
individuals may be "luckier" than others in the company they keep, that this "luck" is a
component of individual fitness and should be counted in some kind of "inclusive fitness", and
that this kind of "luck in your social companions" may be heritable. But this kind of group
selection can only overcome selection at the individual level in some VERY restricted
circumstances. In particular, Price-style groups must engage in a certain amount of outbreeding -
they have to export their altruism before it becomes swamped by home-grown selfishness. Clearly,
a biological species cannot be a Price group - a species never outbreeds.

2. What does it mean for one species to be more fit than another species? Two possibilities. One
(mentioned by Fisher - I just read this today) is that a fit species is one that minimizes its
risk of extinction. The second (championed by Gould, I think) is that a fit species gives birth
to a multitude of descendent species. Either formulation makes sense - but neither is likely to
be subjected to a Popperian test. These are ideas for modeling only.

3. What species-level entity takes the role that genes and traits play in individual-level
selection? It must be a set of species-level traits. Furthermore, they have to be traits that are
"emergent" at the species (or at least population) level. They cannot be "colligative" traits -
for example, they cannot be frequencies of individual genes, nor can they be averages of
individual traits. They cannot, in fact, be quantitative features at all - they probably need to
be discrete, qualitative traits. (I believe that this viewpoint has been championed by Elizabeth
Vrba.) As an example of a discrete, species-level trait, think of a particular ESS in a game
model which allows multiple ESS's. Once a species has fixed on an ESS, the individuals in the
species have to "get with the program" or they will regret it. The ESS is stable as a species
trait, just as a gene is stable. If the species reproduces by fission, then both daughter species
inherit the ESS. Mutation is possible, but if mutation is rare enough, and if the choice of which
ESS becomes fixed has an effect on

4. The interesting thing is that this mechanism can conceivably lead to the kind of Gaia-esque
mutualisms that Dawkins derides. It is possible that an ESS may be an emergent property of a pair
of species, rather than a property of a single species playing social games with itself.

Do I really believe all this? Well, it is possible, at least in theory. But, as with Price-style
group selection, it probably isn't too important in practice in today's world. But, as we OOL
enthusiasts know, any straw may be worth grasping if we want to get Darwin working for us, rather
than relying on some kind of unknown self-organization principle.
 
[email protected] (Huck Turner) wrote

> > The perspective one choses is completely arbitrary. There is no rule or law that tells us that
> > one perspective is better than another.
>
> We can choose to follow some pretty useful rules in evaluating scientific theories. The most
> obvious rule we follow is that we prefer theories that make accurate predictions to ones
> that don't.

I agree.

Less
> obvious, but also familiar is the rule that where two theories make the same predictions (i.e.,
> are notational variants of the same theory) we tend to adopt the simpler variant.

Again, I agree.

We also prefer theories
> that are more general, explaining a greater variety of phenomena, etc.

I agree.

>
>
> > Selection is not a level/unit specific process.
> >
>
> For scientists to be able to make precise predictions from a theory of selection, the theory has
> to be precisely formulated.

I agree. And it's imprecise to assume selection happens to or on a level/unit.

To this end, it
> would be extremely desirable to be able to define precisely what is and what isn't selected.

Selection happens to biological phenomena in its entirety.

>
>
> >
> > It's an issue of parsimony.
> >
> > Parsimony is applicable to hypotheses, not assumptions or unit.
> >
>
> But assumptions are just naked hypotheses,

Assumptions are assumptions.

and just like other kinds
> of hypotheses, gain legitimacy when observations or experiments turn out to be consistent with
> the theory.

AFAIC levels/units of selection are not mutually exclusive. The exact same phenomena when viewed
from the level/unit of the individual (or gene) will be no less consistent with theory when viewed
from any other level/unit.

>
> As for the unit issue, if there is a choice between two theories, one that entertains the notion
> of selection at the species level _only_ and another that entertains the notion of selection at
> the gene level _only_, then yes, they're equally parsimonious, but the situation is not like that.
> Group selectionists believe that there are processes acting at the level of groups, not that group
> selection can account for everything that gene selection accounts for. The question being asked is
> whether we need a theory that combines gene and group level selection, or whether it is sufficient
> to have one that deals with gene level selection only.

I think it depends what you are studying or trying to explain. If you are trying to explain the
origins of a characteristic that afford group benefits then it makes sense to employ the group as
the unit of selection.

>
>
> > You could perhaps come up
> > > with a species level account of a certain set of phenomena, but it wouldn't add anything
> >
> > It would add a different perspective.
> >
>
> Yes, fine, but perhaps the only kind of consistent group level account would be one that doesn't
> make any predictions that don't already follow from a gene level account. A theory like this might
> be useful, but wouldn't be necessary.

Could not the same be said of the gene level?

> > to what a gene level account already provides.
> > > In other cases, a species level account may also make incorrect predictions, which is a more
> > > obvious reason to reject it.
> >
> > Incorrect predictions are possible regardless of the perspective chosen.
> >
>
> Yes of course this applies to both accounts. I was trying to distinguish between two
> conceivable kinds of objections that Dawkins may have to group selection so as not to confuse
> one with the other.
>
>
> > I agree with
> > > him on this (assuming I'm representing his view accurately), but I have to say I don't really
> > > understand the arguments that some people on this newsgroup have made for group/species
> > > selection, so perhaps I could be persuaded to change my mind.
> >
> > Selection doesn't happen on/to levels. It happens to biological phenomena in its entirety.
> >
>
> This definition of selection is too vague to be useful, IMO.

But if it's accurate (and I'm sure it is) then it's usefulness is to allow us freedom from dogmatic
assumptions about unit/level of selection.

Jim
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> Huck Turner <[email protected]> wrote or quoted:
[snip]
> > The only sense my feeble mind can make of the idea of opposing forces of selection is the case
> > where there are two opposing forces at the same level. [...]
>
> Species-level selection should act to make populations more likely to speciate.
>
> For example:
>
> * Members of a population should have genitalia that quickly become incompatible with those of
> their host population if they are isolated from it;

So a species (or set of species) with more easily mutated genitalia will tend to give rise to a
greater number of descendant species and we could say that this is what it means for a species
property to have greater fitness. However, we have no reason to expect the total size of the
population of individuals to change as a result of the speciation event unless the genital mutations
also affect the chances of individuals reproducing. If it has an opposing negative effect on fitness
at the level of the individual (the case that you take to be interesting), we should expect the
total size of the population to decrease while the number of species in it increases until either a
more stable species emerges with less mutable genitalia or the whole lot of them go extinct.

>
> * They should enjoy (and be well adapted to) living on islands - since islands are where many new
> species are born;
>
> * They should be prone to changes in ploidity;
>
> ...and so on.
>

The above reasoning could be applied to these examples too. As the number of species increases, the
total number of individuals may decrease. This is a bit like dividing a cake into thirds, throwing
away one third and then celebrating that now you have two pieces where before you had only one.
Continue this process dividing each of the pieces into thirds and you'll have less and less cake,
but more pieces. This is like the Cantor set
(http://www.mathacademy.com/pr/prime/articles/cantset/).

> These may not be the same traits that best serve individual reproduction.
>
> Indeed the traits the would best serve species reproduction may positively /hinder/ individual
> level reproduction. Genitals that are verging on mechanical incompatibility with other members of
> your species might well make isolated popualitons more likely to speciate - but they might also
> make it more difficult to get a date.

But if they're isolated already then it won't make matters worse if their genitalia are
incompatible so there simply won't be a competing selection pressure for genital compatibility. It
won't be present.

>
> Forces on the different levels can pull in different directions - and favour different
> adaptations.

Doesn't follow.

H.

---
Like-minds don't notice shared mistakes. Talk to someone else.
 
> JM:- Then Dawkins writes: ``The temptation is to think that this second illusion is crafted by the
> same kind of process as the first: by a version of Darwinian selection but at a higher level.
> [...] I believe that this theory is false.'' He goes on to write: ``As Adam Smith understood long
> ago, an illusion of harmony and real efficiency will emerge in an economy dominated by self-
> interest at a lower level. Well balanced ecosystem is an economy - not an adaptation.'' I take
> Dawkins' point - but he goes too far for me. He gives species selection no quarter. He does not
> point out that species selection gets the final word in terms of what lives or dies. He doesn't
> even discuss relative reproductive rates. He just *totally* rejects the whole theory of species-
> level selection as "erroneous".

JE:- Dawkins was right for the wrong reason. Yes, a "well balanced ecosystem is an economy" because
it is powered by organism fitness mutualism (OFM) and _not_ organism fitness altruism (OFA), YET
Dawkins view is classically gene centric where OFA replaces OFM within Hamilton's rule. Dawkins
utterly misrepresented the Darwinian view as Hamilton's gene centric view because Dawkins is a
member of the political left and "prefers" OFA being true within nature. Organism fitness
selfishness (OFS) is preferred by the political right. However, OFA and OFS are logically identical.
You cannot have one without the other. On their own neither can provide an absolute gain in fitness.
All they can do is pass fitness around. In stark contrast to this absurd situation, OFM provides
mutual but not necessarily equal gains and thus ALONE, allows populations to expand via a selected
_association_.

Species are just _additive_ composites of Darwinian fertile organism fitnesses. This being the case,
selection acts FIRSTLY at the Darwinian level BEFORE any species level can even be attempted to be
selected. Therefore species selection can only go with and not against, selection at the Darwinian
fertile organism level of selection. The Darwinian level of selection is the very 1st INDEPENDENT
level of selection that can be measured in nature. This means the fitness of genes, cells and organs
form non additive fitness associations where all these DEPENDENT levels of selection are selected
simultaneously at just the ONE Darwinian fertile organism fitness level. Populations and meta
populations of the Darwinian level only form 2nd, 3rd, etc independent levels that are only selected
AFTER the Darwinian levels HAS BEEN selected.

Respectfully,

John Edser Independent Researcher

PO Box 266 Church Pt NSW 2105 Australia

[email protected]
 
Jim Menegay <[email protected]> wrote or quoted:

> 2. What does it mean for one species to be more fit than another species? Two possibilities. One
> (mentioned by Fisher - I just read this today) is that a fit species is one that minimizes its
> risk of extinction. The second (championed by Gould, I think) is that a fit species gives birth
> to a multitude of descendent species. Either formulation makes sense - but neither is likely to
> be subjected to a Popperian test. These are ideas for modeling only.

Fisher's idea is good - provided he extends the concept to any descentants of the species.

A head count of the resulting species would not work as well as it does with individuals - since
species can vary in size dramatically.

> 3. What species-level entity takes the role that genes and traits play in individual-level
> selection? It must be a set of species-level traits. Furthermore, they have to be traits that
> are "emergent" at the species (or at least population) level. They cannot be "colligative"
> traits - for example, they cannot be frequencies of individual genes, nor can they be averages
> of individual traits. They cannot, in fact, be quantitative features at all - they probably
> need to be discrete, qualitative traits. (I believe that this viewpoint has been championed by
> Elizabeth Vrba.)

[...]

This is all after distinguishing "species selection" from "species sorting" - and *only* considering
the former.

Species sorting may be important. It may produce traits in individuals that apparently make little
sense in terms of short-term selection pressures - and /only/ make sense when considering the
selection pressures present during occasional periodic extinctions.

Your list of "species selection" qualifiers sounds very restritive to me.

It doesn't take much to qualify as an emergent trait. For instance, anything that affects the
resulting speciation rate would immediately qualify, in this context.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove lock to reply.
 
John Edser wrote:

> Species are just _additive_ composites of Darwinian fertile organism fitnesses.

Isn't your emphasized _additive_ mostly the shorthand for a perfect mixing hypothesis ? Why would
your applicable definition for "fitnesses" disallow saying the same of individuals ?

> This being the case, selection acts FIRSTLY at the Darwinian level BEFORE any species level can
> even be attempted to be selected.

If your claim to natural inference is correct, shouldn't the swapping of "Species" and "Individuals"
in the previous sentence, reverse the capitalized order ?

Regards, MC
--
"On naît tous les mètres du meme monde"
 
> JE:- Species are just _additive_ composites of Darwinian fertile organism
> fitnesses.

MC:- Isn't your emphasized _additive_ mostly the shorthand for a perfect mixing
hypothesis ?

JE:- I don't understand what you meant by a "perfect mixing hypothesis".

When things only have an additive association this association does not change
the things so associated, so they remain independent. I argue this is the case
because addition is just a reversible logical process that can be illustrated by
set intersection. OTOH, non additive associations changes the things so
associated so they become dependent. I argue this is the case because non
addition is a non reversible logical process that can be illustrated by set
nesting. Once sets are nested they are trapped. What is important to evolutionary
theory is the difference IN LOGIC between _dependent_ and _independent_ levels of
selection and how this can be described using the logic of pure mathematics.

MCI:- Why would your applicable definition for "fitnesses" disallow saying the
same of individuals ?

Individuals are not just "populations" of genes, cells or organs. Just the sum of
any of these parts do _not_ make an individual. The same argument applies to the
_fitness_ of somatic genes, cells or organs. The fitness of these parts are
_dependent_, i.e. they are all selected at just the one, same, level of
selection. This will be the first independent level, i.e. the first level that
can be tested within nature to act independently. This can be demonstrated to be
Darwin's single level of selection: the fertile organism level.

> JE:- This being the case, selection acts FIRSTLY at the Darwinian level BEFORE
> any species level can even be attempted to be selected.

MCII:- If your claim to natural inference is correct, shouldn't the swapping of
"Species" and "Individuals" in the previous sentence, reverse the
capitalized order ?

JE:- No, because the concept of the individual is _not_ irreversibly nested
within a species concept. Darwin proved this when the fixity of species was
refuted by him. The relationship between species and individuals is just
additive, i.e. any species and its fitness IS the sum of the individuals and
their fitnesses, that form it. This being the case, selection must act FIRSTLY at
the Darwinian individual level. Selection at the species level can only be
completed AFTER selection at the Darwinian level has finished operating because
the Darwinian individual level of selection (the fertile organism level) is
_empirically_, the first _independent_ level of selection that actually exists
within nature.

Respectfully,

John Edser Independent Researcher

POI Box 266 Church Pt NSW 2105 Australia

[email protected]
 
Tim Tyler <[email protected]> wrote in message news:<[email protected]>...
> Jim Menegay <[email protected]> wrote or quoted:
>
> > 3. What species-level entity takes the role that genes
> > and traits play in individual-level selection? It
> > must be a set of species-level traits. Furthermore,
> > they have to be traits that are "emergent" at the
> > species (or at least population) level. They cannot
> > be "colligative" traits - for example, they cannot be
> > frequencies of individual genes, nor can they be
> > averages of individual traits. They cannot, in fact,
> > be quantitative features at all - they probably need
> > to be discrete, qualitative traits. (I believe that
> > this viewpoint has been championed by Elizabeth
> > Vrba.)
>
> [...]
>
> This is all after distinguishing "species selection" from
> "species sorting" - and *only* considering the former.
>
> Species sorting may be important. It may produce traits in
> individuals that apparently make little sense in terms of
> short-term selection pressures - and /only/ make sense
> when considering the selection pressures present during
> occasional periodic extinctions.
>
I am not familiar with the term "species sorting". Is it a
standard terminology for a standard concept?

Whatever the term means, extinction is a species-level
phenomenon that affects individual survival. A species
survives if it contains individuals with high (long term)
individual fitness. Therefore, I think that it is more
productive to describe the kinds of issues you are talking
about as an aspect of individual-level selection, rather
than by species-level selection.

> Your list of "species selection" qualifiers sounds very
> restrictive to me.

I wasn't aware that I had provided a "list". My intention
was to sketch out some criteria, and to give some examples
of consequences. See below.

>
> It doesn't take much to qualify as an emergent trait. For
> instance, anything that affects the resulting speciation
> rate would immediately qualify, in this context.

Two criteria for identifying a species-level trait that may
be subject to species-level selection:
1. The trait must be emergent at the species level. A fleet
herd of deer should be interpreted as a herd of fleet
deer. Fleetness is not emergent, and should therefore be
explained by individual-level selection.
2. The trait must be persistent/heritable at the species-
level. A long-lived species will usually retain the trait
without change. If the species fissions, both daughter
species will inherit the trait from the parent species.

Ultimately, of course, any species-level trait is explained
to a reductionist by some kind of system of interactions
among individual-level traits. Hence my mention of ESSs.
Defector/cooperator can be viewed as either an individual-
level or a species-level trait. It is not obviously
emergent unless there is a dynamics that makes it
persistent at the species level by offering incentives at
the individual level.

My insistence that species-level traits must be qualitative
rather than quantitative is based on an intuition that only
qualitative traits can be sufficiently persistent/heritable.
But, I may be wrong on this.

To respond now to your point: I don't think that *anything*
that affects the speciation rate qualifies. You have to have
emergence and persistence/heritability, otherwise the
phenomenon is better described at the individual level. For
example, if a species is good at speciating because its
individuals are good at dispersing, then that should be
viewed as individual-level selection.

diploid sporulation and haploid somatics, then its
speciation success should be attributed to species-level
selection.

IMHO. Well, maybe I should say IMO.
 
Jim Menegay <[email protected]> wrote or quoted:
> Tim Tyler <[email protected]> wrote in message
> news:<[email protected]>...
> > Jim Menegay <[email protected]> wrote or quoted:

> > > 3. What species-level entity takes the role that genes
> > > and traits play in individual-level selection? It
> > > must be a set of species-level traits. Furthermore,
> > > they have to be traits that are "emergent" at the
> > > species (or at least population) level. They cannot
> > > be "colligative" traits - for example, they cannot
> > > be frequencies of individual genes, nor can they be
> > > averages of individual traits. They cannot, in
> > > fact, be quantitative features at all - they
> > > probably need to be discrete, qualitative traits.
> > > (I believe that this viewpoint has been championed
> > > by Elizabeth Vrba.)
> >
> > [...]
> >
> > This is all after distinguishing "species selection"
> > from "species sorting" - and *only* considering the
> > former.
> >
> > Species sorting may be important. It may produce traits
> > in individuals that apparently make little sense in
> > terms of short-term selection pressures - and /only/
> > make sense when considering the selection pressures
> > present during occasional periodic extinctions.
>
> I am not familiar with the term "species sorting". Is it a
> standard terminology for a standard concept?

Pretty much, I think now. Vrba, Eldredge and Gould are the
folks mostly making use of the term, though. Searching for
it should provide many instances of its usage.

> > It doesn't take much to qualify as an emergent trait.
> > For instance, anything that affects the resulting
> > speciation rate would immediately qualify, in this
> > context.
>
> Two criteria for identifying a species-level trait that
> may be subject to species-level selection:
> 1. The trait must be emergent at the species level. A
> fleet herd of deer should be interpreted as a herd of
> fleet deer. Fleetness is not emergent, and should
> therefore be explained by individual-level selection.

The speed of a herd of deer is a group phenomenon - which is
not simply the additive sum of the running speeds of
individual deer. If it were, the fastest deer would migrate
to the front, and the herd would stretch out into a long
line. The deer would also have no reason to head in the same
direction. Factors such as the size of the herd will
influence their collective running speed - and are simply
not a factor for an individual deer.

In practice, the idea of group or species traits being
simple sums of individual trats rarely stands up to close
inspection. Often, there are some emergent properties of
some kind involved.

> I don't think that *anything* that affects the speciation
> rate qualifies. You have to have emergence and
> persistence/heritability, otherwise the phenomenon is
> better described at the individual level. For example, if
> a species is good at speciating because its individuals
> are good at dispersing, then that should be viewed as individual-
> level selection.

> diploid sporulation and haploid somatics, then its
> speciation success should be attributed to species-level
> selection.
>
> IMHO. Well, maybe I should say IMO.

I expect being good at speciating via dispersal and being
good at reproducing via dispersal are actually different
things, though.

Being good at speciating via dispersal probably means being
good at speciating onto remote islands - and they have to be
extra-remote if the rest of your gene pool is also good at
hopping between islands.

Indeed, ISTM that humans are pretty good at dispersal - but
are not showing many signs of being good at speciation just
yet. It seems that there's more to speciating than merely
travelling well.
--
__________
|im |yler http://timtyler.org/ [email protected] Remove
lock to reply.
 
Tim Tyler <[email protected]> wrote in
news:[email protected]:

> Jim Menegay <[email protected]> wrote or quoted:
>
>> 2. What does it mean for one species to be more fit than
>> another species? Two possibilities. One (mentioned by
>> Fisher - I just read this today) is that a fit species
>> is one that minimizes its risk of extinction. The
>> second (championed by Gould, I think) is that a fit
>> species gives birth to a multitude of descendent
>> species. Either formulation makes sense - but neither
>> is likely to be subjected to a Popperian test. These
>> are ideas for modeling only.
>
> Fisher's idea is good - provided he extends the concept to
> any descentants of the species.

Some random thoughts (and I think all my thoughts on this
topic are still pretty random):

There apparently is research (see reference in 13 Feb 2004
Science p.
973) that speciation is more rapid in polyandrous
species,apparently as

reproductive traits. But does this make the species more
fit?

On a population ecology level, many species exhibit density-
dependent reproduction. This may help stabilize a species
from extinction due to wild population swings, but only some
of the mechanisms (migration, increased territoriality)
appear to have an individual benefit. Others (stress shock,
infant mortality) would only be valuable at the species
selection level.

Gould's idea is interesting. If genera that give rise to
many species have a longer lifespan than genera that don't,
then mechanisms that give rise to speciation will be
selected (although I have difficulty calling such mechanisms
"adaptations", because they will for the most part be
otherwise selectively neutral.) There was an interesting
article in Science several years ago (apparently August
19,2001 by Henikoff, Ahmad and Malik) that mentioned
centromere variability as a mechanism for speciation.
Perhaps this is an example of species selection?

sometimes been cited as an example of species level
selection - the

> A head count of the resulting species would not work as
> well as it does with individuals - since species can vary
> in size dramatically.

>> 3. What species-level entity takes the role that genes
>> and traits play in individual-level selection? It must
>> be a set of species-level traits. Furthermore, they
>> have to be traits that are "emergent" at the species
>> (or at least population) level. They cannot be
>> "colligative" traits - for example, they cannot be
>> frequencies of individual genes, nor can they be
>> averages of individual traits. They cannot, in fact,
>> be quantitative features at all - they probably need
>> to be discrete, qualitative traits. (I believe that
>> this viewpoint has been championed by Elizabeth Vrba.)
>
> [...]
>
> This is all after distinguishing "species selection" from
> "species sorting" - and *only* considering the former.
>
> Species sorting may be important. It may produce traits in
> individuals that apparently make little sense in terms of
> short-term selection pressures - and /only/ make sense
> when considering the selection pressures present during
> occasional periodic extinctions.
>
> Your list of "species selection" qualifiers sounds very
> restritive to
> me.

> It doesn't take much to qualify as an emergent trait. For
> instance, anything that affects the resulting speciation
> rate would immediately qualify, in this context.

Right. These properties are going to be "emergent", since
they will only be important at the species level. They have
to be traits that differ between species, but this is true
of many traits. I suppose "average" traits would be tougher
to work with at the species level, but I think we need to
list some examples. For instance, size might be considered
an "average" trait, but a species with small individuals
occupying a similar ecological niche will have a larger
population than a species with larger individuals, and will
be more likely to survive an extinction event.

Yours,

Bill Morse
 
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