Re: Selection timescale
From: Guy Hoelzer (hoelzer_at_unr.edu)
Date: 02/03/05
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Date: Thu, 3 Feb 2005 14:54:52 -0500 (EST)
in article ctfbbu$2e7i$1@darwin.ediacara.org, Jim McGinn at
jimmcginn@yahoo.com wrote on 1/28/05 10:44 PM:
[snip]
>>> I don't much care how easy it is to define or describe the idea of
>>> fitness - but I am concerned with whether what it defines serves as
>>> a reasonable organism-level proxy mother nature's maximand.
>>
>> And here we have the crux of our disagreement. You want to define fitness so
>> as to validate the adaptationist program - nature maximizes fitness - BY
>> DEFINITION.
>>
>> I want to define fitness so as to facilitate the "dynamicist program".
>> Evolutionary change can be modeled dynamically because the dynamical
>> variables, such as gene frequencies and type populations are modified by
>> selection according to the fitnesses of genes and types.
>>
>> And Hamilton's rule offers a perfect example why we cannot both be satisfied.
>> Selection acts according to an organism's basic fitness. Yet it is inclusive
>> fitness that turns out to be maximized. I have no doubt that some future
>> Hamilton, investigating some other aspect of nature besides social behavior,
>> will find still more discrepancies between selection's criterion and nature's
>> maximand. And will define yet another kind of "inclusive" fitness to bridge
>> the two concepts.
>
> Well, you're asking all the right questions.
>
> If fitness is a commodity that can be expressed with units what are
> these units.
I would argue strongly that fitness is not a commodity. As I have often
argued on sbe, fitness is a heuristic concept of great value, but it has no
natural (physical) existence. It is much more like a currency than a
commodity. Fitness also represents a kind of statistical thinking that is
abstract relative to physical causality. This is why we can only estimate
the fitness of a new individual, say based on its genotype, but we (e.g.,
John Edser) often think that we can observe an individuals fitness if we
track its survival and reproductive success over its entire lifetime. While
I disagree that an individual's fitness can ever be determined without
contingency (e.g., as a statistical probability), I doubt that anybody would
disagree with my claim that fitness cannot be known at birth as a matter of
principle.
> Are they fully translatable to any of the different ways a lifeform
> might achieve its fitness (survival, reproduction, assisting others to
> survive/reproduce)?
No.
> Is fitness a commodity or is it commoditizable.
It is commoditizable by assumption as an abstract statistical parameter, but
not as a result of any natural process.
> How can we, from a theoretical perspective, get a quantitative grasp on
> this?
Good question.
Guy
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