speciation

"friend" <[email hidden]> wrote

Quoted message said:

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.)

Quoted message said:

* 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.

Quoted message said:

* 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.

Quoted message said:

* 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.