Re: Reproductive Selection

On Mon, 17 Dec 2007 23:25:15 -0800 (PST), Treus <treusdrie@xxxxxxxxx>
wrote:

That argument is a retread with lots and lots of toy balloons and a
clown suit. I'm not impressed. Of course there are instances where
there is no need to "generate compatibility". That's been agreed
already. Are you claiming that every, or even most, of the species
alive today that require RC in order to reproduce can be traced as far
back in time as you like without finding an ancestor with respect to
whom the living specimen did not need to "generate compatibility"? If
so, please name a species.

That's a pretty convoluted sentence, but I believe the obvious answer
is "all of them".

Compatibility exists already and is inherited. Any change in the
genome that produces incompatibility in one generation ends with that
individual. You'd probably call that reproductive selection. With a
nod to our friend backspace, let's not forget that selection is not a
"force"; in this case the negative version is simply "failure to
reproduce".

Since all organisms fail to reproduce with their distant ancestors*
(by virtue of not living at the same time), the theoretical ability or
inability to do so cannot be acted on by selection. If you disagree, I
think you'll need to explain how selection can act where there is no
advantage or disadvantage, as is always the case among groups that
have no chance to interbreed.

Evolution produces changes in the genome. Changes in the genome in a
single generation that do not inhibit reproduction at all will not be
selected against on that basis. Changes that slightly reduce fertility
between the "new" and "old" genotypes but increase the rate of
survivability to a greater degree will be selected for despite the
"cost" in fertility. Moreover, that decrease in fertility will
disappear if the trait becomes fixed in the population, and thus does
not compund itself over time.

If you disagree with that last bit you'll have to explain how
selection, which is a shorthand term for "how many criiters with
certain traits live to reproduce, and how much", can always favor
fertility over other factors, even if the net result (of lower
fertility + greater survivability) yield more young in the next
generation.

There. That's my convoluted sentence for the day.

Greg Guarino

* I'm sure one of the overachievers on this group will come up with an
exception. Long-dormant seeds, perhaps?

.

Relevant Pages

  • Re: Reproductive Selection
    ... there is no need to "generate compatibility". ... alive today that require RC in order to reproduce can be traced as far ... You'd probably call that reproductive selection. ... had NO other effect other than to lower fertility. ...
    (talk.origins)
  • Re: Reproductive Selection
    ... there is no need to "generate compatibility". ... alive today that require RC in order to reproduce can be traced as far ... You'd probably call that reproductive selection. ... Changes that slightly reduce fertility ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... compatibility over time is paradoxical in the context of natural ... at least as far as natural selection is concerned. ... *unrelated factor in the environment be less suited to reproduce than ... Reproductive incompatibility is not only a matter of "equipment". ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... compatibility over time is paradoxical in the context of natural ... at least as far as natural selection is concerned. ... *unrelated factor in the environment be less suited to reproduce than ... Reproductive incompatibility is not only a matter of "equipment". ...
    (talk.origins)
  • Re: Reproductive Selection
    ... there is no need to "generate compatibility". ... alive today that require RC in order to reproduce can be traced as far ... You'd probably call that reproductive selection. ... Changes that slightly reduce fertility ...
    (talk.origins)