Re. Wings

[John Grehan]

In reply to Rikki Hall

Orthogenesis is the concept of evolution occuring without
natural selection being necessary for that evolution to occur.

>Was there more to this sentence?

Likely, but I've forgotten what else went with it.


More likely, half of its offspring will get
>the novel gene.

My understanding (which I admit may be inadequate) is that the gene
from one parent will convert the gene from the other so the offspring will
not be heterozygotes.

>
>Your scenario only includes offspring of the one initial mating, and
>naturally there would be many more matings among individuals not bearing
>the mutation in a real population.  On the population level, then, the
>presence of the mutation would be much more dilute, even after a few
>generations of 100% mutant survival.

Since it converts all other loci (I may not have the right word here) it will
spread just in the same way as a disease (except in this case the individuals
are not suffering debilitating effects).

>
>Still, though, I understand what you are describing.  It is the neutral
>theory of Kimura, which posits that many mutations have little effect on
>their bearer's fitness, and the process of drift, whereby allele ratios
>change stochastically and not because of selection.


No you are not quite correct. The genes may be neutral with respect to
selection,
but they are not simply stoachistic independant genes. Rather there appears
to be a mutational bias in the first place (the orthogenesis concept), and a
conversion of the same site to that new mutation so it spreads through the
population.


 This stuff is
>standard evolutionary biology and not some major alternate theory,
>though your careless math makes it seem more powerful than it is.

As clarified above, the math does not apply, and its not Kimura's neutral
gene theory.


>Surely you wouldn't claim that the possession of wings, even weak,
>barely functional wings is a neutral mutation offering no improvement in
>survival, dispersal, or mate acquisition, would you?

While I cannot go back into the past to determine an actual case, I WOULD
indeed consider that senario a possibility to the origin of wings.


>If there were no fitness differential, then we should still be seeing
>populations with some fractional portion bearing wings and some majority
>retaining the ancestral wingless state.

Since there is a conversion process involved I would not expect that situation.


>So how did we end up with millions of insect species whose populations
>are uniformly winged?  I suppose that they are not species at all, but
>merely mutants fragments of the Insectan ultra-population?  or the
>Arthopodal ultrapopulation, or the Invertebrate ultrapopulation?

Not sure what this question is getting at, but it may be covered by the
above.

 Do you acknowledge a species concept?

Yes, my preference is for the concept of species as spatiotemporally bounded
entities without essence.

My position on orthogenesis is derived from biogeography, not genetics.
However there are geneticists moving towards concepts that appear to have a
similar, if not identical, process implied.

I am not a molecular geneticist, so I leave the details of debate about the
mechanisms they propose to argumentation among the molecular genetisists
(although I have disucssed these matters with some to check on my
interpretations). I am interested in the genetic proposals in their
concordance with orthogenesis (albeit modified from the concept proposed by
Haacke) and other concepts such as reciprocal co-construction.

If you are interested more in the genetic details I may suggest the following:

Dover, G. A. 1986. The spread and success of non-Darwinian novelties. In
Evolutionary processes and theory (eds. S. Karlin and E. Nevo), pp 199-237.
Academic Press, Orlando, Florida.

Dover, G. A., and Strachan, T. 1987. Molecular drive in the evolution of
immune superfamily genes: the initiation and spread of novelty. In
Evolution and vertebrate community (eds. G. K. and D. H. Schulze), pp.
15-33. University of Texas Press, Austin.

In general summary, I see a world of evolution where natural selection
interacts with biased genetic mutation. I see a world where the origins of
structures, behaviours etc, may have originated and spread through a
population without there being any immediate advantage to the individuals
concerned in terms of reproductive fitness.

It is possible that the establishement of these new structures etc
themselves changed the course of evolution for these groups, so that, for
example, with the evolution of wings insects did fly, in fact they may have
had no choice. I realize this is a minority position, so much so that by
definition most people would regard me as a nut. Perhaps so, perhaps not.

Our great library does not appear to have the book you mentioned. i will have
to interloan a copy.

Sincerely, John Grehan