"friend"  wrote
>
> I wondered if there were any views on the following:
>
> * 'unused' stretches of genome are workspace (somewhat like
> 'genetic RAM')
>
I don't like this analogy at all (at least as far as our present
understanding goes). There is some evidence that introns separate genes into
functional domains, and that this facilitates gene shuffling. (Rather on the
principle that if you move the telly, an armchair, and a rug round the room
at random you have a reasonable chance of coming up with a liveable
arrangement. However if you break the telly into electonic components,
dismantle the armchair, and pull the rug into threads, and toss them all
about at random, your chances of producing a decent living room are very
small.)
>
> * speciation is more likely when workspace has converged
> (become less random)
>
If you don't accept proposition 1, this one is pretty meaningless. maybe if
you gave a bit more detail we'd know what your teacher is getting at.
>
> * mutation does not necessarily make speciation more likely
>
I think this is true. For instance mutations in the immune system don't tend
to produce speciation, because animals mate disassortively to present a
constantly varying defence to pathogens.
>
> * speciation is more likely as a result of a selection pressure
> which cannot be adequately 'solved' by dna ('used' or 'unused'
> stretches)
>
Duh. We have hardly ever observed speciation in the field. However it seems
likely that disruptive selection has got to lead to speciation eventually.
It may be that dna can become "used" or "unused"
depending on circumstances,
and that this can give the organism a flexibility that delays speciation,
however as far as I know there isn't any firm data on this. Again you need
to know exactly what the person making this proposition is looking for
before you can really answer.
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