Re: Species Selection Redux

From: William Morse (wdmorse_at_twcny.rr.com)
Date: 03/11/05 

Date: Fri, 11 Mar 2005 01:01:43 -0500 (EST)

Wirt Atmar <atmar@aics-research.com> wrote in
news:d0adoi$1v8i$1@darwin.ediacara.org:

(snip)

> If everything that I have said to this point is true, and if I were to
> launch a research program on this question, then I would focus my
> interest on the differences in the climatic and environmental
> histories of the two continental basins. The notion of "diversity
> pumps" is an idea that comes and goes, falling in and out of favor,
> but it's a idea that I have always tended to favor.

I will wait to comment on several of the subjects raised in your post
until I have viewed the talks on latitudinal diversity gradients - this
is definitely an important topic in speciation.

> These questions are also related to the question about Gould's
> contributions, One important question that he asked was: If we could
> run the tape of life again, would we get the same results? His answer
> was no. Evolutionary outcomes are dictated by the happenstance of
> lucky fits and starts. But his answer isn't mine. To my eye, the vast
> majority of the evidence points towards certain inevitabilities, and
> the convergences ane parallelisms that we commonly find in extant
> biota are the most overt evidence of those inevitablities. If you also
> look and listen again to what Meyer has to say in his slide 21, you
> have to be at least a little astounded at the qualtiy of the
> convergences in morphology (and most likely behavior)in the ciclids in
> the several African lakes. These convergences appear to be very clear
> evidence of the tape of life being run over again, at least on a small
> scale, and having the same results recur.

Yes, slide 21 is rather stunning. Barlow has a single line drawing in his
book (page 224) that is taken from that slide (at least I assume so since
the credit is to Axel Meyer), but seeing the actual slied is pretty
impressive. And the species in Lake Victoria, despite having only had 1/2
million years to diverge, and being mostly of one genus with a total
genetic diversity less than that of homo sapiens, have clearly started to
develop the same variety of specializations.

Now some could argue that there are certain developmental possibilities
for cichlids, so most of the convergence is due to the limitations
inherit in cichlid ontogeny. There is probably some truth to this, but I
would suggest that those arguers also take a look at pictures of the
heads of a kangaroo and a deer.

As a further point, Meyer does not discuss social behavior in his talks,
but for those who want to believe in contingency I would suggest a
reading of chapters 8-11 of Barlow's book on cichlids alongside a text on
social behavior of primates. It would appear that most of the range of
social arrangements seen in primates (harems, monogamy, assistance in
raising kin) can be predicted based on ecology - there is a lot of
predictability in social structure between taxa separated by half a
billion years of evolution.

 
Yours,

Bill Morse