[Taxacom] Dispersal... again

[Jason Mate]

OK, back to work. Please find my points below.
Michael, are we talking about continental drift or genetic drift? The literature you offered as ?New Modern Synthesis? is just population genetics in evolutionary biology, which is a continuation of the work of Haldane and Dobzhansky. In any case you are not explaining how the application of random genetic forces applies to your version of vicariance and neither do Lynch nor Stoltzfus. In fact they point fingers at the non-mathematically inclined biologists that place too much stress on selection (i.e. most of us in TAXACOM). Still I find their work to be similar to Wright?s shifting balance theorem, although I admit not goint over their papers carefully. Nevertheless, they stress not the organisms but the genes. In this point they differ from Mayr, for whom the genes were interdepent so the unit of selection was the genome, which was as well shielded from the outside by the phenotype. Notwithstanding this, he recognised the role that random genetic forces (drift, mutations, recombination) had in the evolution of populations and species.
You keep bringing THE quote from 1965 as it somehow defines his ideas, but his body of work speaks otherwise. Maybe he did not make it sufficiently clear that continental drift was yet another interruption in gene flow but his ideas do not contradict it so most people are OK with them. In fact if I look at your statement:
 ?...a widespread ancestor 'breaks down' into subordinate groups by repeated, non-random mutation.?
and Mayr?s 1976 quote: "Not all population discontinuities in nature originate by the colonization of islands. Sometimes they arise by the contraction of a species range and the separation of a previously continuous area into separate ranges." (Mayr 1976)?
It is obvious that the second part of the statement is perfectly compatible with vicariance of any sort. So I am not sure why you take issue with it. Furthermore your own quote is parapatric speciation paraphrased.
Mayr, in the historical context and with the data of the 40?s, 50?s and 60?s was correct. You are judging him in hindsight, enjoying the benefits of the huge advances in population genetics and phylogenetics. Did Mayr make mistkaes? Yes, he did, from our present context. Not accepting recognising speciation was a mistake, but the tools to work out this have only been commonly available for the last 30 years. Not recognising your version of vicariance (I am still trying to figure out what it is) is at best an oversight.
So, going back to dispersal, I have some questions to ask. How does a species achieve a ?wide range? if not by spreading out from somewhere? Doesn?t this entail an initially smaller range? At what level does speciation occur in your scenarios? I am of the opinion that it is at the level of (panmictic) populations but maybe you have other ideas? What is the distinction between ?dispersalist?ideas and yours? What distance covered counts as dispersal?

Best
Jason 
P.D. I am not familiar with any Mayr 1980?s in The Auk other than that on subspecies. Is it the same one?