Re: The Paradox of Speciation

On Dec 3, 1:25 am, treusd...@xxxxxxxxx wrote:
Al wrote:
On Dec 3, 1:49 pm, treusd...@xxxxxxxxx wrote:
Garamond Lethe wrote:

Maybe you could start by outlining why you think RM+NS is insufficient
for speciation and work from there.

I've been doing so. The "speciation" (you could call it "grand
speciation") that I am talking about, and without which there could
not evolve the diversity of life now observed, entails a
discontinuity, manifested either suddenly or by degrees, in
reproductive compatibility over time. To the extent that mutation
causes this, either suddenly or by degrees, it also reduces the
fitness of the organism by reducing its viability with prospective
mates (whose reproductive systems are either as inherited or randomly
varied with respect to the individual in question).

The problem you're trapping yourself with is that "prospective mates"
idea. Once there's geological (or other, but geo is easier to
visualize) seperation,

Yes, geo works well. Stands for all.

those two populations don't share prospective
mates.

True, but they do share reproductive morphologies (at least at the
moment of original isolation), so compatibility within their
respective subgroups (required directly by natural selection) equals
compatibility with the other subgroup (required indirectly, as a
consequence of the previous requirement, by natural selection).

As far as within a population is concerned, there will always be some
drift, and small amounts at any one time have no real affect, but over
time this will create geneticly different populations, even when the
population looks and behaves exactly as it did at the beginning of the
experiment. And that's not supported with some clever logic, just the
old experimental evidence stuff. Whatever effects are holding back
variation to the old genetics, are loosing out on average to the
effects pushing for change.

That sort of change does happen, no doubt. However, "grand
speciation" (i.e. backward incompatibility of reproductive morphology
over an arbitrary interval of time) can't be explained in terms of
mutation and natural selection alone.

Let's see how it works out with a concrete example:
Take the Indian Elephant (Elephas Maximus), and the African Elephant
(Loxodonta Africana)

1) Do you agree that those populations are geographically isolated,
with little hope for exchange of genetic material ?

2) with your peculiar definition of "species", do you consider those
populations different species, or the same species ? Please justify
your answer.

3) Do you agree both populations share a common ancestor species ?

4) How the so-called "advantage of reproductive compatibility" can
affect two population that are out of contact with each other. Please
explain the precise mechanism.

.

Relevant Pages

  • Re: Bipedalism in different substrates
    ... >>their mothers are on such ground. ... > our own species and would have been shared to a considerable extent ... major one about the speciation. ... >>that it has any bearing on how populations ...
    (sci.anthropology.paleo)
  • Re: The Paradox of Speciation
    ... Anatidae, which has 150 species ... laboratory populations, and there are many experiments that show this. ... even if there is strong selection against ... reproductive compatibility between populations. ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... laboratory populations, and there are many experiments that show this. ... So you will first have to revolutionize our species concepts ... even if there is strong selection against ... reproductive compatibility between populations. ...
    (talk.origins)
  • Re: population sizes for colonising a planet
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    (rec.arts.sf.composition)
  • Re: Reproductive Selection
    ... different from whatever ancestor is taken as the starting point. ... the two allele model) there's nothing keeping the populations from ... (which is a problem philosophers have with the biological species ... speciation spontaneously reverse. ...
    (talk.origins)
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