Re: Evolution of Separate Genders in Animals


"Nic" <harrisondalen@xxxxxxxxxxx> wrote in message news:1173156238.666200.146440@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 6 Mar, 03:30, "Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx>
wrote:
"derdag" <der...@xxxxxxxxxxxxxxxxxxxx> wrote in messagenews:1173149609.317443.107100@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Mar 5, 8:45 pm, "Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx>
wrote:
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"Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx> wrote in message
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"r norman" <r_s_norman@xxxxxxxxxxxx> wrote in message
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On 5 Mar 2007 12:09:35 -0800, "hersheyh" <hershe...@xxxxxxxxx> wrote:

On Mar 5, 12:35 pm, "derdag" <der...@xxxxxxxxxxxxxxxxxxxx> wrote:
On Mar 5, 5:46 am, "SJAB1958" <balf...@xxxxxxxxxxx> wrote:

Can anyone help me out with a query? I know that the swapping of
genetic material between organisms arose before the formation of
separate genders, but did separate genders come before
hermaphrodites
or was it the other way round? Any website links that would help
here
would be greatly appreciated.

When evolution decided ...

"Evolution" does not 'decide' anything. That would be ignorant
anthorpomorphism. Unlike our dear Prez, evolution is not the
'decider' of anything. Local environmental conditions, OTOH, are the
the dumb, unintelligent decider between variants based on how well
those variants reproduce.
<snip>

When normal people say that evolution "decides" or "chooses", it is
simple anthropomorhic shorthand, a common practice among the
cognoscenti. When derdag says it, it is plain ignorance, not
specifically anthropomorphic ignorance.

And, lest derdag think we are picking on him, notice that he did
write: 'A couple of them had the same idea at the same time.' A couple
of what? A couple of species? No evidence that it would have been
at the same time. A couple of individuals? Individuals don't 'decide'
in any sense in the ToE.

How about suicide?

Well, OK. Or the decision to have a large family. Or the decision to
migrate. Individual decisions can influence the direction in which
population gene frequencies go. However, they cannot result in heritable
genetic mutations.

Well, OK. The decision to become a worker in a nuclear plant or an
airline pilot. But individuals in a population of asexual reproducers
don't 'decide' to reproduce sexually instead and pass that trait on to
their children. Which is what I think derdag was suggesting.- Hide quoted text -

- Show quoted text -

derdag did suggest that there was a problem at the time some and I
mean (one) cell underwent meosis instead of mitosis, needing a proper
(irreducibly complex) structure present for combining with another
haploid cell (and there must have been only (one other one) to become
a diploid cell. It could do it several times and there would still
only be one cell. God Bless you for putting up with this stupidity.
lol I realize that if this occured in a sex cell of a multicelled
organism, that the problem would be somewhat less complex in that
way. However, if that were the case we would need two organisms to
develope the lock and key mechanism and find eachother.

Lets just assume that the other poster is right and that mitosis
became meosis in a single celled organism. The other problems are
even more complex. (1+1) becomes (1) and (1); and then (1) and (1)
combine to become (1+1) again.

Man, that works out pretty sweet.

Meiosis is more complicated than you seem to think. It is not (1+1) becomes
(1) and (1). It is more like (1+1) becomes (1+1+1+1) which then becomes
some number between one and four of (1)s. Probably fusion - (1) and (1)
become (1+1) - was already a well developed behavior long before meiosis,
with its complex sequence of events got 'invented'. And it is also likely
that the nuclear aspects of this sexual dance were developed in a polynucleate
cell. Only later did the nuclear events become obligately linked to cytoplasmic
fission and fusion. IMO.

I agree with that last point. It is still difficult to imagine
systems intermediate between mitosis-only, and meiosis/fertilisation
plus mitosis.

I'm wondering whether mitosis is really the same process in the
haploid and diploid case. I.e are they both equally agnostic about
chromosome pairing by homology? (The relevance of that question is
that I'm wondering if originally only the haploid phase could
multiply, and that meiosis/fertilisation were originally an
indivisibly scripted sequence within a 'conjugation' of some sort.)

I think that is quite likely. Also that 'conjugation' was a response
to some kind of lack of raw materials or DNA damage. The original
purpose of recombination was DNA repair. But doing so results in
Holliday junctions half of the time, and half of the time resolving
them results in a crossing-over.

.

Relevant Pages

  • Re: Evolution of Separate Genders in Animals
    ... mean cell underwent meosis instead of mitosis, ... if that were the case we would need two organisms to ... Meiosis is more complicated than you seem to think. ...
    (talk.origins)
  • Re: Evolution of Separate Genders in Animals
    ... separate genders, but did separate genders come before ... mean cell underwent meosis instead of mitosis, ... if that were the case we would need two organisms to ... for crossing-over during meiosis. ...
    (talk.origins)
  • Re: Evolution of Separate Genders in Animals
    ... separate genders, but did separate genders come before ... mean cell underwent meosis instead of mitosis, ... if that were the case we would need two organisms to ... for crossing-over during meiosis. ...
    (talk.origins)
  • Re: Evolution of Separate Genders in Animals
    ... mean cell underwent meosis instead of mitosis, ... if that were the case we would need two organisms to ... Lets just assume that the other poster is right and that mitosis ... both nuclei have all the required genes it needs. ...
    (talk.origins)
  • Re: Evolution of Separate Genders in Animals
    ... mean cell underwent meosis instead of mitosis, ... if that were the case we would need two organisms to ... *many* copies of each gene and does not divide by mitosis. ... both nuclei have all the required genes it needs. ...
    (talk.origins)