Re: Group selection in the breeding of super chickens
- From: "John W Edser" <edser@xxxxxxxxxxxxxx>
- Date: Wed, 13 Feb 2008 13:41:01 -0500 (EST)
dkomo <dkomo871@xxxxxxxxxxx> quoted:-
"Today's models of group selection are as gene-centered as any other
models of natural selection, including Hamilton's explanation of the
evolution of altruistic traits. Many biologists are now quite
comfortable with the idea that kin selection is a form of group
selection, in which the interacting kin group is the target of
selection, and the unit whose frequency changes during selection is the
gene."
Jablonka, _Evolution in Four Dimensions_, p. 37
JE:-
What "the idea that kin selection is a form of group selection" means is
that sterile reproductives and their parents constitute one grouped
selectee. My point: a family and its immature offspring constitute just the
one unit of selection because sterile reproductives have a zero fitness.
IOW this group is _not_ classically group selective. Sterile forms cannot
be considered independent units of selection and cannot be deemed altruistic
in fitness simply because they have no fitness to lower. Sterile
reproductives are more like somatic cells than anything else. I am not
attempting to split hairs, simply providing a _falsifiable_ theory as to
what empirically constitutes one selectee within Darwinian theory while
maintaining Darwinism as monocentric. In contrast, Hamilton's polycentric
inclusive fitness minimally allows three selectees which _biologically
contradict each other_. These are: c which is the Darwinian fitness of the
donor, b the transfer of resources from the donor to the recipients
increasing their Darwinian fitness accordingly and r, the relatedness of
each recipient to the donor. Note that b is always > 1 making Hamilton's
argument _classically group selective_ while simultaneously allowing r to
reduce inclusive fitness to also be gene centric (deleting all gene fitness
epistasis in the process). Each of these supposed independent levels of
selection contradict each other leaving Darwin's parent to be reduced to the
meat in just a mathematical sandwich.
A group is a set of organisms tightly coupled enough that their
fitnesses are dependent on the fitnesses of the other members.
JE:-
No. What you have described above is one biological individual which must
remain fertile just to have any fitness. Groups of fitness independent
individuals remain _interdependent_ and not dependent. Mathematically, the
difference is critical. The fitness of one fitness interdependent group will
be equal to the simple sum of the fitnesses of all independent members
within that group. OTOH the fitness of an dependent group will remain non
additive (epistatic).
snip<
Regards,
John Edser
Independent Researcher
edser@xxxxxxxxxxxxxx
.
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