Larry Moran wrote:
> On Mon, 8 Mar 2004 04:12:39 +0000 (UTC), 
> William Morse  wrote:
> 
>>lamoran{at}bioinfo.med.utoronto.ca (Larry Moran) wrote in
>>news:c25pfm$4j0$1{at}darwin.ediacara.org: 
> 
> 
> [snip]
> 
> 
>>>How does one distinguish between a just-so story and a valid
>>>explanation? If it turned out that Asian elephants had big ears and
>>>African elephants had small ones do you think that someone would come
>>>up with an adaptionist explanation? I do. That's the problem. With
>>>sufficient imagination one can conjure up an adaptionist explanation
>>>for almost anything that happens in biology. This isn't a very good
>>>reason for preferring adaptionist explanations over chance and
>>>accident - expecially since we know for a fact that chance plays the
>>>major role at the molecular level. Why shouldn't it play a major role
>>>at the morphological level as well? 
>>
>>How major a role?  
> 
> 
> If we compare homologous genes from different species the vast majority
> of differences appear to be neutral with respect to fitness. Thus, it
> appears that random genetic drift is responsible for most of evolution
> when measured by actual changes in the fixation of new alleles. This
> doesn't take into account the role of negative selection in eliminating
> detrimental alleles but that's not what we're discussing. One question 
> is whether positive natural selection accounts for a significant 
> proportion of change at the molecular level. This doesn't seem likely.
> 
> What about the mechanism of evolution for alleles that have an obvious
> phenotype? Is it only natural selection or drift involved? I don't know 
> what you might consider a "major" role. Right now I'd be
happy just to 
> see adaptionist admit to the possibility that some morphological traits 
> can be fixed by accident.
> 
Just to make you happy, I'm prepared to admit that this can happen. 
Indeed, I'm happy to submit an example: the kink in the tail of the 
Florida panther.  It's explained as being due to inbreeding, which seems 
a perfectly acceptable mechanism to me.

Or is the kink an adaptative response to hanging chads?

Bob

-- 
Bob O'Hara

Dept. of Mathematics and Statistics
P.O. Box 4 (Yliopistonkatu 5)
FIN-00014 University of Helsinki
Finland
Telephone: +358-9-191 23743
Mobile: +358 50 599 0540
Fax:  +358-9-191 22 779
WWW:  http://www.RNI.Helsinki.FI/~boh/
Journal of Negative Results - EEB: http://www.jnr-eeb.org
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