[Taxacom] Dispersal... again

[Michael Heads]

Hi Curtis,
?
Without 'mutational bias' you could probably do a lot of compararive biogeographic analyses of groups in space and time. But when it comes to a consideration of organic form (either morphological or molecular), intrinsic bias is?much, much more effective than random mutaton followed by selection. In this second, modern synthesis, approach,?the effort is on finding any current functions of organs and explaining their origin by their end (teleology).?With the modern synthesis, unless you're a taxonomist, you're not so interested?any more?in comparative studies of other organs in other groups, and so you don't see particular morphologies as merely parts of broader trends. When presented with an unexplained?structure, you just want know what it's for. The modern synthesis sees organs as formed in response to?extrinsic needs, imposed by the 'conditions', not by prior, intrinsic mutation biases. ?These biases produce long term trends in morphological
 change, such as reduction and fusion in the vertebrate pharynx, and in the flower, and may play out in parallel over tens or even hundreds of millions of years in countless?environments with completely different conditions.???

Michael

Wellington, New Zealand.


My papers on biogeography are at: http://tiny.cc/RiUE0


________________________________
From: Curtis Clark <lists at curtisclark.org>
To: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu>
Sent: Friday, 28 October 2011 5:27 PM
Subject: Re: [Taxacom] Dispersal... again

On 10/27/2011 7:54 PM, Michael Heads wrote:
> Mutation bias [...]

Let me try again. If mutation is truly random, and mutation bias 
unimportant, does panbiogeography lose some of its explanatory value? 
I'm trying to understand how big is the required buy-in.

(I actually think the evidence for mutation bias is compelling, although 
I'm still not sure how much of a role it plays.)

-- 
--
Curtis Clark
Cal Poly Pomona


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