Re: Reproductive Selection

Ernest Major wrote:

In message
<c41a60f0-f9f5-483d-99f2-09fcd6b2a7d9@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Treus <treusdrie@xxxxxxxxx> writes


Greg Guarino wrote:

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".

And the obvious follow-up is: "What is your empirical evidence?" A
case in point addressing one species will do. Then we can proceed.


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".

The metaphorical "force" is used in this context in the literature. It
works .


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,

Okay, so the incompatibility disappears. You still don't have then new
compatibility of S2 where S2 is a remote descendent with a
significantly novel set of characteristics uniquely necessary to the
RC of S2. Perhaps you can provide an example from observation. What
are two species where one descended from the other and the later type
has a significantly novel (with respect to the ancestor type) set of
characteristics that are uniquely necessary to its own RC, and that
evolution was according to what you have described)?


In the previous thread John Harshman offered you a Mimulus. (I think
from the description that it was Mimulus cupriphilus, but I don't recall
the epithet being mentioned.)

The publications I looked at didn't give it separate species status, but
considered it just a population of M. [I forget the specific epithet].
There is some question whether a population separated *only* by
post-zygotic isolating mechanisms should be considered a full species.
After all, in the absence of strong selection for adaptations to
different habitats, one of them would drive the other into extinction.

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.

It does not. This point has been made several times.


And we're left wondering where your argument is. Once you have conceded
that the mean of the population with respect to factors affecting
fertility can change we are left wondering what mechanism you propose to
stop it changing indefinitely.

.

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: Newbie Questions
    ... Natural selection can only improve a species' s lot by selecting from ... reproduce early and often over those who spread their reproduction out ... suited to their environment tend to go extinct when the environment ...
    (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: 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: Reproductive Selection
    ... 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 ... You'd probably call that reproductive selection. ... Changes that slightly reduce fertility ...
    (talk.origins)