Re: The Paradox of Speciation

treusdrie@xxxxxxxxx wrote:


John Harshman wrote:

Truesdrie@xxxxxxxxx wrote:


John Harshman wrote:


treusdrie@xxxxxxxxx wrote:



John Harshman wrote:



Mate choice is just as capable
of creating reproductive isolation as anything else.


Which is why I have made the distinction several times between
reproductive isolation and reproductive incompatibility.

So your species concept is not the usual one in biology. This creates
difficulties in communication. And there are practical problems with
your concept too. See below.


That's right. The definition of "species" I am using is not the usual
one and that seems to be causing you a lot of trouble. This
communication would generation much less internet clutter if you would
stop bringing up the usual definition and accept the one I am using
here. Or, if difficulties remain, we can drop "species" altogether and
just use "reproductive compatibility" which is probably better
anyway.

It would be nice if you had mentioned from the beginning that you have a
personal definition for several terms that differs from everyone else's.

I don't. My defintion of "species" is not the most common one but it
is found in certain nternet dictionaries. Besides, the term "species"
is not necessay since "reproductive compatability" is more to the
point anyway. Problem solved.

All this tells you is that internet dictionaries are not the best place
to look for definitions of biological terms.

Are you actually trying to blame other people for misunderstanding you
in that case?

No since I have made several claifications.

If you had been clear from the beginning, none of this would have been
necessary. A lesson for the future.

I don't find your "reproductive compatibility" to be at all biologically
meaningful. You seem to consider it an all or nothing thing, while there
are continuous intermediates in nature between perfecctd intersterility
and perfect interfertility.

The presnce of intermediates is irrelevant here. At some point a
reproductive system evolves that breaks continuity and thereby self-
isolates, and I'm still waiting for you to describe how that is
selectively advantageous.

This seems to assume some kind of saltation. There is nothing of the
sort needed. There is no "at some point". As with any continuum, where
you want to draw the line is arbitrary. I have already given you several
examples of ways in which the evolution of reproductive incompatibility
can be neutral; doesn't have to be advantageous.

Do you have any hypotheses?


Nothing to argue on a scientific basis, which all I care to do here.

Let's not be coy. You have something in mind. Why not admit what it is?

It's not about being coy. The various ideas I have on the subject
would be off-topic and not add to this discussion.

I have to think you have some more important reason for not bringing
them up.

Are you a mind reader?

No, but I am capable of drawing reasonable inferences from observing
behavior. Could be wrong, but that's my current hypothesis. It would be
easy for you to show me wrong by just explaining your alternative.

Do you think we would all point and laugh? Knowing this
newsgroup, that's not unlikely. But so what? How thin-skinned are you?

I've already indicated that my personal ideas on speciation are still
tentative and would take this thread way off-topic besides.

You don't mean "speciation", right? You mean the evolution of
reproductive incompatibility, which is quite a different thing.

And of course your position is wrong, and does not survive contact with
what we know. In fact increased reproductive isolation is fairly easy to
select for in laboratory populations, even when you aren't trying. There
are many experiments that show this.

Not "reproductive isolation", but rather "reproductive
incompatibility". Though there is an overlap, it's better to avoid
ambiguity.

"Reproductive isolation" is at least a term in general use. I'm not sure
exactly what you mean by "reproductive incompatibility". If you mean
post-mating or post-zygotic isolation, these too can be selected for in
laboratory populations, and there are many experiments that show this.

Two individuals are reproductively compatible if they are capable of
producing offspring together.

That's not a very useful definition; by that definition many members of
separate species, at least as currently understood, are reproductively
compatible. So you will first have to revolutionize our species concepts
before we can talk at all. How many species of ducks would you say there
are? I think there are about 150, but by your rules there may only be 1.
Is that a good idea? Many populations that live separately in sympatry
would by your criterion be one species. Are you sure you've thought this
through?

Okay, let's drop "species" and go with "reproductive compatibility"
exclusively then.

So your claim is that two populations that were once one population can
never lose reproductive compatibility, even if they become separate
species living sympatrically, even if there is strong selection against
hybrids. Right?

Pretty close, but I'll clarify. My claim is that reproductive systems
that are as widely compatible (including backwardly compatible) as
possible are most favorable to the fitness of the individual and will
thus be selected for. A group arising with a reproductive system that
is incompatible with that of its progenitors (and consequently
virtually all of its contemporaries at every step of in the evolution
of the new morphology) requires a mechanism other than mutation and
natural selection.

I have already explained more than one mechanism that would make this
possible. You tend to ignore them.

To whit:

1. Different selective regimes that have the byproduct of reducing
reproductive compatibility between populations.

2. Drift of gene location in different populations.

There are many more.

.

Relevant Pages

  • Re: The Paradox of Speciation
    ... Anatidae, which has 150 species ... laboratory populations, and there are many experiments that show this. ... even if there is strong selection against ... reproductive compatibility between populations. ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... laboratory populations, and there are many experiments that show this. ... So you will first have to revolutionize our species concepts ... even if there is strong selection against ... reproductive compatibility between populations. ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... reproductive isolation and reproductive incompatibility. ... So your species concept is not the usual one in biology. ... laboratory populations, and there are many experiments that show this. ... never lose reproductive compatibility, ...
    (talk.origins)
  • Re: Do you actually BELIEVE THAT?
    ... new genetic information. ... complete change and divergence into species. ... populations are isolated from each other, ... reproductive isolation, nor is it even an example of geographic ...
    (talk.origins)
  • Re: The Paradox of Speciation
    ... reproductive isolation and reproductive incompatibility. ... So your species concept is not the usual one in biology. ... I don't find your "reproductive compatibility" to be at all biologically ... laboratory populations, and there are many experiments that show this. ...
    (talk.origins)