General fitness, health and nutrition · Public discussion

Mutualism

Started by Jim Menegay · · Last activity · 1 post · 467 views

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General fitness, health and nutrition
Published
2 April 2004
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2 April 2004
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Jim Menegay
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  1. "John Edser" <[email hidden]> wrote in message news:<[email hidden]>...

    Quoted message said:

    JM:- Fisher's "fundamental theorem" says that the
    genetical component of fitness is non-decreasing.

    JE:- This is consistent with the Darwinian proposition
    that each parents absolute fitness (the _total_ number of
    _fertile_ forms reproduced by _each_ parent into _one_
    population) cannot be selected to be reduced, i.e. at all
    times parents must maximise the total number of fertile
    forms they reproduce into one population.

    JM:- But he avoids having continuously increasing
    populations by claiming that the environment is
    continually deteriorating. Only recently have theorists
    realized that Fisher was including the average fitness of
    competing conspecifics as a component of the environment.
    So, we have a "Red Queen" race - fitness continually
    increases, but number of offspring do not.

    JE:- Most populations have been observed to expand and
    then become more stable. Populations that only tend to
    decrease are on the road to extinction.

    JM:- A minor quibble: extinction is inevitable only if the
    trend of population decrease persists. But populations have
    also sometimes been observed to contract and then become
    more stable. This frequently happens after an environmental
    change. At the risk of transforming the minor quibble into a
    major one, it could also conceivably happen after a genetic
    innovation inside the species.

    For example, a large population of small shrubs could
    transform itself into a smaller population of taller,
    broader quasi-trees. (Why has so little been written about
    the sociobiology of plants? In theory, they should play a
    mean game of iterated prisoner's dilemma - they are stuck in
    long term relationships with neighbors and should have no
    trouble remembering who defected. And they can retaliate, if
    necessary by strangling encroaching branches.)

    Quoted message said:


    JE:- If each parent must maximise the total number of
    fertile forms it reproduces into one population (_not_
    just one genomic genes count which can be indicated by the
    presence of that gene in _either_ immature sterile forms
    or fertile forms) populations should keep expanding until
    they reach a stable fluctuation. These are indicated by r
    and K points respectively, observable within most
    population curves. Thus r selection operates during a
    geometric increase well below the carrying capacity of the
    environment but K selection must operate at an
    environmental ceiling capacity. It is here that a
    population can degrade its environment, and it is here
    that all the trouble starts. Can _individuals_ be selected
    to limit their numbers at this point to avoid destruction
    of their environment? Is such an event an altruistic act?
    Is group selection or Hamiltonian logic required to
    maintain an environment?

    JM:- At this point in your analysis, I would like to repeat
    my recommendation of the following paper: "Fisher's
    fundamental theorem of natural selection", Steve Frank and
    M. Slatkin, 1992 stevefrank.org92TREE
    R.html They list two different K-selection strategies
    available at this point. (They overlook the third one
    that you are going to suggest.) Their two strategies are
    (1) grab a bigger piece of the pie, thus reducing K for
    everyone else and reducing the population, or (2) use
    your piece of the pie more efficiently, increasing your
    fitness without hurting anyone else - until the next
    generation when the population creeps up and everyone has
    to accept a smaller piece.

    Quoted message said:

    JE:- I contend that organism fitness mutualism (OFM) can
    select Darwinian individuals to mutualise their
    reproductive output in concert with all the other life
    forms that form its environment requiring no altruism and
    no group selection.

    Van Valen's Red Queen hypothesis supposes that a war
    exists within nature between an expanding population and
    all the other living forms that constitute its
    environment. This produces the effect that all the species
    concerned have to "run harder and harder just to stand
    still", i.e. in order for every parent to produce an
    obligatory absolute fitness increase it has to face
    _increasing_ offence/defence costs. Such a solution is not
    sustainable. OFM enters this situation to decrease these
    costs substantially but not necessarily equally, for all
    concerned. This will include a measure of "the average
    fitness of competing conspecifics as a component" but such
    an average hides _all_ the selective events that are
    occurring at the Darwinian fertile organism level of
    selection. Van Valen's view is organism fitness selfish
    (OFS). Logically such a view is the same as organism
    fitness altruistic arguments (OFA) because what is taken
    by OFS produces an OFA deficit. What is being ignored is
    organism fitness mutualism (OFM) which stands in
    contradiction to both OFA and OFS. It is OFM that
    dominates nature and it is the deceptively simple logic of
    OFM that has been neglected within Neo Darwinian reasoning
    because OFA has dominated for over 50 years.

    JM:- I pretty much agree with this, except that I would add
    the following points:
    1. True OFM is a relationship between two, or a few,
    organisms - not a relationship between an organism and
    its species.
    2. Mutualistic associations protect themselves against
    deadbeats by enforcement behaviors; at minimum the
    deadbeat is thrown out of the association.
    3. True OFM relationships can exist between organisms in
    different species, but the restriction to direct organism-to-
    organism relationships still holds.
    4. Insect eusociality is not true OFM, nor is a behavior
    that benefits self and just "accidentally" happens to
    benefit other members of the species (c<0, b>0). True OFM
    requires reciprocity.
    5. Examples of true OFM are pair bonding, "friendship",
    hunting bands, lichens, mitochondria and their hosts, and
    even ritualized territorial displays between songbirds.
    (Sometimes, the best that OFM can do with a finite pie is
    to avoid wasting time dividing it!)
    6. A hypothesis of true OFM is refuted if repeated defection
    does not elicit enforcement behaviors. In that case, we
    have to consider the hypothesis that that sucker really
    IS altruistic.

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