Re: Van Valen's MAXIMAND
- From: Tim Tyler <tim@xxxxxxxxxxx>
- Date: Thu, 19 May 2005 00:17:35 -0400 (EDT)
John Edser <edser@xxxxxxxxxx> wrote or quoted:
> Tim Tyler tim@xxxxxxxxxxx wrote:
> Subject: Re: Van Valen's MAXIMAND
>
> > > JE:-
> > > In order to measure any relative fitness, i.e. any fitness
> > > difference you must (at the very least) have two fitness totals/sub
> > > totals to compare. In order to have these you have to define a
> > > minimum of two independent selectee's each of which has been
> > > allocated one total/subtotal fitness. What are your two independent
> > > selectee's and what are their total/sub total fitnesses using the
> > > metric you have proposed? If the fitness totals are only sub totals
> > > then their comparison will not be definitive for any natural
> > > selective result.
>
> > TT:-
> > E.g. biomass of species 1 and biomass of species 2.
>
> JE:-
> Does this mean that you are comparing the "biomass of species 1 and
> biomass of species 2" in order to determine which species is selected
> for and which is selected against? If so: please more exactly define the
> two selectee's
That would be the members of species 1 and species 2 at a point in time.
> and then define the units of fitness that can be calculated for each of
> them.
That would be grams.
> You must state if each compared biomass is a total or just a subtotal
> for each selectee you have defined.
It's not clear how one would one distinguish between a total and a
subtotal in this context.
> > > JE:-
> > > Success at what?
>
> > TT;-
> > Becoming an ancestor.
>
> JE:-
> Do you argue that "becoming an ancestor" was causative to evolution or
> was it just the result of another (unnamed) cause? If "neither" please
> explain your position.
Becoming an ancestor can cause future evolutionary events, and can
be the result of another cause, though probably not "just" the result
of another cause - depending on what that is supposed to mean.
> > > JE:-
> > > Why didn't you answer/criticise the question?
>
> > TT:-
> > The question was about what I was saying. In my answer I explained
> > what I meant. I don't think entities with more biomass will always
> > win out - but I do think biomass may well be a better guide to success
> > than counting individuals is.
>
> JE:-
> Yes, but within the sciences it is simply not enough for just you to
> "think". You have to explicitly explain your thinking to others who's
> job is to remain sceptical. The question I asked was designed to allow
> you to make a more specific explanation to sceptics.
>
> Do you agree or disagree that the logic of natural selection requires a
> comparison of at least two fitness total/sub totals where all units of
> fitness and at least two independent selectees must be defined as
> countable objects/forces of _biology_?
I'm not sure what "countable objects/forces of _biology_" are - but
most of the rest of that sounds reasonable enough.
> > > > > JE:-
> > > > > I cannot see any rational fitness in comparing biomass or total
> > > > > counts of individuals for different _species_.
>
> > > > TT:-
> > > > I was comparing whole families, not individuals from them.
>
> > > JE:-
> > > But it can be proven empirically that a fitness competition does
> > > exist between any fertile family members so what is the use of this
> > > metric and how does it relate to the empirical Darwinian metric TDF?
>
> > TT:-
> > That was "families" - as in: phyla, orders, families, genera, and
> > species - not "families" as in the Smiths and the Joneses.
>
> JE:-
> Ok. Your answer requires you to be much more specific. I will start with
> species. If species compete then one unit of selection has to be one
> grouped unit called "one species". If fitnesses are to remain self
> consistent then species must reproduces other species and not just
> individuals within the same species grouping. Do you accept this point?
Clearly species enjoy differential reproductive success.
They divide and form offspring species in a manner similar to the
way asexual organisms reproduce.
> > > > TT:-
> > > > Each species (or family, or phylum) has some chance of being a
> > > > long-term ancestor - i.e. of having some distant descendants - and
> > > > that's one of the things we use fitness for - to see whether some
> > > > entity's genetic material is going to survive or be obliterated.
>
> > > JE:-
> > > I agree that such a long-term "fitness" can be a useful but entirely
> > > heuristic concept. My question is: are you suggesting that it can
> > > replace the empirical Darwinian concept of fitness as I have defined
> > > it?
>
> > TT:-
> > I'm afraid I don't always keep track of your definitions.
>
> Here it is, yet again. [...]
So what are you asking again? Is it a drop-in replacement for
that sort of fitness? No. It it another definition of fitness
with other applications? Yes.
[...]
> > TT:-
> > A consequence of the idea is that species trading body size against
> > the numbers of individuals supported in a given environment should
> > not necessarily be regarded as being any less fit - simply because
> > there are fewer of them.
>
> JE:-
> My biological understanding is that species (groups) cannot firstly
> compete because they are always comprised of independently selectable
> Darwinian _individuals_.
This is contrary to biology textbooks, which at least recognise group
selection as a phenomenon exhibited in the laboratory.
> I cannot see any use of forcing a selective
> competition between two different species via your metric of biomass (or
> anything else) while just ignoring the result of selection between
> individuals which always happens *FIRSTLY*. No empirical evidence exists
> for species competition acting in disregard to the Darwinian fertile
> form level which always acts first. All the evidence points to
> competition firstly acting between fertile individuals within a species
> as Darwin originally implied. So called
> independent gene fitness do not even exist in NATURE. Do you agree or
> disagree that the level that operates firstly must dominate all other
> levels within any multi level proposition?
Gene level and individual level selection are probably the most
important levels. IMO, we can't see the strength of higher-levels
of selection very clearly yet - except to say that thay are not obviously
strong. What we can say is that the higher levels definitely at
least exist, and can't be discounted.
> > TT:-
> > What matters more is how effective they are at utilising
> > environmental resources which they are in competition with
> > other species for - and their collective biomass can do
> > reasonable duty as a proxy for that.
>
> JE:-
> You have to more exactly define what they are utilising environmental
> resources *FOR*.
Organisms are usually regarded as being "for" transforming resources
into offspring in biology.
> If and when you define it more exactly you end up making a maximand
> proposition of nature.
My essay on the issue of what nature is maximising is this one:
http://originoflife.net/bright_light/
As a brief summary, I don't think the question can be answered neatly,
but I tend to regard thermodynamic metrics as the most fundamental -
with my favourite such metric being the rate of entropy increase
caused by the system in question.
No single metric will ever be ideal, since organisms compete for
resources on a multi-dimensional landscape - and maximisation
on different timescales fundamentally requires different metrics.
> So far you have failed to provide such a definition. Van Valen has
> provided one but it is non refutable. Darwin implied one which remains
> refutable to this very day. To my knowledge these are the only
> evolutionists that have proposed a maximand for evolutionary theory.
IMO, there are literally dozens of definitions of fitness, each of which
plays the role of a proposed biologial maximand. IIRC, at one stage there
was a survey that identified in excess of 20 distinct definitions of
fitness in the literature.
--
__________
|im |yler http://timtyler.org/ tim@xxxxxxxxxxx Remove lock to reply.
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