[Taxacom] Dispersal example

[John Grehan]

Curis,

"You and others seem to promote it
as a "clean" science, unencumbered by extraneous theories and
data-focused, but if indeed it relies on a specific mode of evolution
being pervasive, that seems to be a weak spot. If someone showed
conclusively that mutation bias played no role in evolution, would
panbiogeography fall?"

Ha! Would that science be so simple. Let?s first turn that question around
and ask ?If Darwinism relies on a specific mode of evolution being
pervasive, that seems to be a weak spot. If someone showed conclusively
that mutation bias played no role in evolution, would
Darwinism fall?



I guess it comes down to what is ?conclusively?. As shown by how different
people respond to something being demonstrated, the ?conclusively? can be
an elusive concept. I would argue that the Darwinian mode of evolution
involving centers of origin and dispersal has been conclusively shown to
have played no role in evolution (as differentiation). But does that mean
everyone agrees that this is conclusive? No, but would anything be so
regarded as conclusive? Some biogeographers ended their days denying the
conclusively of stable continents.



And then there is the molecular clock divergence theory that was said (by
various proponents) to have conclusively falsified panbiogeography, and yet
it rested on a false representation of the evidence.



As I presume you know (and presumably anyone on this list who at least
teaches biogeography), panbiogeography has two principal aspects ? the
method and the synthesis. The latter has been generated by the former. At
least as I see it, the latter would not falsify the former. The synthesis
presented a predication as to the mode of differentiation not being
determined by natural selection that seemed to be necessary with respect to
how differentiation occurred spatially (vicariously). It so happens that in
the field of genetics there are models of evolution that are concordant
with that prediction. Of course there are also genetic models that are in
conflict with that prediction.



Apparently Einstein?s theory of relativity was conclusively falsified the
day after it was published (not sure if that ?day after? is apocryphal, but
the point being that the relativity theory did not immediately disappear in
a puff of smoke).



So it?s an interesting question to which there may not be a single
universal satisfactory answer any more than there is for Darwinism.



John Grehan




On Sun, Apr 20, 2014 at 9:26 PM, Curtis Clark <lists at curtisclark.org> wrote:

> On 2014-04-20 2:27 PM, Michael Heads wrote:
> > Most of us were taught the old idea that mutation is random and that
> > the course of evolution is determined by selection. But many
> > geneticists now think that mutation is biased and that this bias can
> > in itself determine evolution. This has been argued by Masatoshi Nei,
> > one of the pioneers of molecular biology and evolution (his work has
> > been cited 196000 times). His latest book - nice and short and clear -
> > is called 'Mutation-driven evolution'. (OUP, 2013)  This idea is
> > compatible with Darwin's later work (post-1859) where he rejects his
> > earlier panadaptationism (this is always 'overlooked' by the so-called
> >  'neodarwinians'), and also with Croizat's 'orthogenesis'.
>
> I'm familiar with the arguments (although I have not studied them
> deeply), but it is unclear to me whether and how they are necessary to
> the basic tenets of panbiogeography. You and others seem to promote it
> as a "clean" science, unencumbered by extraneous theories and
> data-focused, but if indeed it relies on a specific mode of evolution
> being pervasive, that seems to be a weak spot. If someone showed
> conclusively that mutation bias played no role in evolution, would
> panbiogeography fall?
>
> --
> Curtis Clark        http://www.csupomona.edu/~jcclark
> Biological Sciences                   +1 909 869 4140
> Cal Poly Pomona, Pomona CA 91768
>
>
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