Defining&testing "macroevolution" (was: Testing the Laws of Intelligence)



From: "mel turner" <mtur...@xxxxxxxxxxxxxxxxxxxxxxx>
As for its meaning, "microevolutionary" seems pretty clear to me:
having to do with microevolution, in other words having to do with
evolution of populations below the level of speciation.

And what is *that* supposed to mean? How does one decide whether a
given act of evolution (a single mutation, or a single
recombination, or a single death of an individual which changes
population statistics, or a single geologic event which changes the
connectivity between various populations) is or is not "below the
level of speciation"?

For example, if all the chromosomes in a plant suddenly double,
making the resultant plants reproductively isolated from all
members of their parent species, is that below the level of
speciation? I'm guessing you'd say no, that's macroevolution
instead.

If a mountain pass becomes impassible, thereby separating two
populations of what was formerly a single species, what about that?

If two populations have 78% cross-fertility, compared to 100% within
either single population, but a mutation in one of the populations
decreases the cross-fertility to only 77%, what about that?

If successive mutations in one or another of the two populations
gradually decrease the cross-fertility from 99% down to less than
one percent, which of the individual mutations is considered to be
the event which crosses the line, no longer "below the level of
speciation"?

Or is every one of the individual events (except wholescale
chromosome duplication) considered "microevolution", and
"macroevolution" is nothing more than a sufficiently long sequence
of microevolution events?

I'm not expecting a concensus definition at this point. I just
expect any *individual*, such as **you**, to precisely define these
terms for your own usage such that it's possible for an external
observer to apply your definitions rigorously to decide each
individual case in a consistent way. But the key matter is whether
a million events of microevolution can equal an act of
macroevolution, or whether macroevolution requires some special
kind of event that is all by itself beyond the limits of
microevolution. You must define your terms, or quote somebody else
who defined them in a way you find acceptable; put up or shut up.

Even speciation [= "macroevolution"] can be observed on
timescales much shorter than millions of years.

Until you specify what definition you are using, that statement has
no meaning. Speciation is clearly nothing more than the accumulated
sequence of tiny events. Is one of those events considered
"macroevolution" all by itself, or is "macroevolution" nothing more
than a large quantity of "microevolution"? If
million*microevolution = macroevolution, then the demonstration of
microevolution, plus the demonstration of deep geological
evolutionary time, is sufficient to prove macroevolution.

Could she [Zoe] select for some sort of dramatic changes in her
hypothetical bacteria over a reasonable timescale?
[and thereby demonstrate speciation]

Bacteria don't reproduce sexually, hence they don't have presence
or absence of reproductine isolation (or actually fractional
inter-fertility), hence the term "speciation" has no objective
meaning for bacteria. Now if you are willing to precisely define
what you mean by "speciation" per bacteria, maybe we can talk, but
at present what you said above seems to be useless for demonstrating
evolution of bacteria which is not "below the level of speciation".

Again, I was disputing that she necessarily needed millions of years
to do what she said she wanted [depending on how much change would
satisfy her].

I understood her to be requiring demonstration that a single
species can split and subsequently diverge to become as different
as chimpanzees and humans are nowadays. Such a transformation
requires millions of years. I understood her *not* to be satisfied
with little bits and pieces of such a transformation which could be
accomplished within a few thousand years, each single bit/piece
demonstrated in a separate clade with merely a hypothesis that over
geological/evolutionary time all the various bits/pieces might
occur within a single clade.

AFAIK, she was only talking about breeding for some sort of
"macro" change in a hypothetical strain of bacteria,

Whatever "macro" means in that context has nothing to do with
speciation, so why did you even mention the phrase "below the level
of speciation" in this thread?? You pretend like you understand
what Zoe is requesting, yet you jump around between totally
incompatible interpretations of what she *might* have been talking
about. If she's asking about bacteria, then she can't be talking
about speciation, and vice versa. I make no pretense of
understanding what Zoe means, nor even claim that Zoe means
anything specific in the first place. As far as I can tell, Zoe is
just throwing out gobbletygook to try to trip up everyone else. You
seem tripped at present.

But would an investigation looking for some sort of impressive result
of long-term strong selection on bacteria need such a long study?
I suppose that depends on what would impress Zoe or other creationists
who might hold out for a change into something that wasn't "still just
a bacterium".

Now you're not just tripping, you've fallen flat on your face.
The total biomass of "just bacteria" (appx. twenty different phyla)
might be larger than all other biomass put together. Common descent
driven by mutation + fecundity + natural selection explains all
that diversity (in principle anyway). How does Zoe explain it?
If "microevolution" (of bacteria) means "still just bacteria", then
microevolution is sufficient to explain *all* of that diversity!!
Is Zoe willing to submit on that point?

By the same trick of words, evolution of animals results in
"still just animals", so would evolution from primitive sponges
to all the arthropods and chordates and mollusks and thirty other
phyla of animals be considered "microevolution" in the same way?

Perhaps
you aren't aware that there are documented cases of "speciation"
(what I prefer to call species-splitting, a special case of
lineage-splitting)
I'd say that speciation is very much the same thing as cladogenesis,
and not any special case [other than occurring in the present or
immediate past as opposed to earlier in the history of a lineage].

<http://dictionary.reference.com/search?q=cladogenesis>
evolutionary change by the branching off of new species from common
ancestral types.
If we travel upstream from the lower Mississippi to the upper
MIssissippi or to the Missouri or to the Ohio, are we now in a
"new" river that we weren't in before?? I don't see that the word
"new" has any precise meaning in that definition, so I reject it.
n. The evolutionary change and diversification resulting from the
branching off of new taxa from common ancestral lineages.
"taxa" (plural of taxon) is a **name**, not a fact of nature. This
definition seems to say that if we now have two names for the two
sub-populations of what formerly all used the same name, then
something real has happened. Accordingly I reject this definition too.

I give up. What's your favorite definition of "cladogenesis"?

Besides the relatively few possible known examples of ring species are
the much more numerous cases in the gray area between "clearly forms
of one species" and "clearly separate but related species".

Yes, I agree. The main advantage of a "ring species" over a mere
spread species is that over millions of years the two overlapping
ends of a "ring species" have clearly not interbred sufficiently to
maintain genetic closeness, so we have a clear obvious case where
they are "two different species" as viewed locally. With a non-ring
spread species, the only way to test whether the endpoints can
inter-breed is to conduct breeding experiments, whereby the results
can be disputed as "conditions weren't suitable for breeding due to
scientists using improper procedure, just like when trying to breed
pandas in captivitiy". Not to mention the cost of extensive
breeding experiments to test the hypothesis. Think of ring species
as the "poster child" for transitional forms during speciation
processes. (Speciation isn't an event that suddenly happens. It's a
process that may take hundreds of thousands of years from start to
end. It only seems to be an "event" when viewed via the fossil
record where we might have only one clump of fossils every couple
million years along any particular line of descent.)

It just can't be tested in a controlled experiment.

Or, perhaps much of it can on a somewhat smaller scale with organisms
such as bacteria and fruitflies.

If "still just a bacterium" invalidates work with bacteria, then
likewise "still just an insect" invalidates work with fruitflies.
With bacteria, species isn't rigorously defined, so you might as
well give up trying to convince a naysayer. That leaves frultflies
where speciation is well defined yet might occur within the course
of a multi-year but sub-century experiment.

The question is, what tests does Zoe expect to be made? We can
reasonably expect to be able to show speciation or at least
speciation-in-progress, and to show new adaptations arising by
selection.

Adapations aren't *new*, they're adapted from earlier traits, by
definition. Demonstration of improved adaptions would simply show
(to Zoe) improvement within a basic kind of trait. I think we need
to go with speciation (species-splitting) processes if we hope to
pin Zoe to the wall and force her to agree to the test criterion
and then present evidence she must either accept or look even
stupider than Behe.

.



Relevant Pages

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