[Taxacom] Dispersal... again

[Michael Heads]

Hi Jason,
?
As usual, my comments are given below.
?
Michael

Wellington, New Zealand.


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


________________________________

From: Jason Mate <jfmate at hotmail.com>
To: Taxacom <taxacom at mailman.nhm.ku.edu>
Sent: Saturday, 29 October 2011 8:52 PM
Subject: Re: [Taxacom] Dispersal... again



Hi Michael,
As I am off now to the field til tuesday I think we all have time to think our rebuttals carefully as this discussion is getting us nowhere.
?MH: No, it's completely different. The new model is opposed to the modern synthesis model and in many ways is derived more directly from the geneticists, i.e. the original geneticists such as T.H. Morgan (Nobel prize for genetics but ridiculed in the modern synthesis for not understanding genetics). The earlier workers saw the direction of evolution as due to mutation, in the modern synthesis it is due to selection and adaptation. The new model has very different interpretations of these key concepts, as well as 'gene pool', and all the others.? Michael Lynch has an interesting 2007 book: 'The origins of genome architecture'. These broad genomic changes can be happening throughout a population (e.g. broad shifts in CG composition), not because of random mutation in an individual followed by gene flow, adaptation and selection. ?
Michael, I really don?t know what you are leading to. Morgan was the leading figure of genetics with a Nobel to boot for ?solving? inheritance (chromosomes as the units of information), so yes we agree he was a big fish (also popularized D.melanogaster as the workhorse of genetics). What I don?t understand is why you say he was ridiculed (and by whom). 

MH: He was ridiculed by most of the architects of the modern synthesis?as a 'mutationist' because he did not support?panselectionism?(nor did the older Darwin).

He rejected sexual selection, so this could be the source of some criticism, but by and large the man was a neodarwinian. His ?A Critique of the Theory of Evolution? supports Darwinian Selection.

MH: But he was not a panselectionist.?

, supplying the rather important piece of inheritance, without which it was fatally flawed. Furthermore he stressed the importance of mutations in the same vein as other [Jason: you've missed out something here] He invited Dobzhansky as a foreign researcher, the same Dobzhansky that wrote the seminal ?Genetics and the Origin of Species?. Morgan even suggested the title! The book is practically the synthesis. It just needed Mayr, Gaylord Smith and others to give it mass appeal (OK Fisher and Haldane made important contributions but Dobzhansky is the true father of population genetics and the modern synthesis), establishing populations as the units of evolution, balancing selections (natural selection, mutation, migration, drift..) as the forces that resulted in genetic variability (this variability was the Achilles heel that De Vries, Johannson and other anti-darwinists attacked!). So once again, Lynch is not postmodern synthesis but additional work
 in population genetics.

MH: Have you read his book? Whatever you call his approach, it's definitely not modern synthesis.?His 2007 PNAS paper is titled: "The frailty of adaptaive hypotheses for the prigins of organismal complexity'.?Here's a typical modern synthesis assessment of Morgan: ?As late as 1932 T.H. Morgan was asserting that
?natural selection does not play the role of a creative principle in
evolution,? but ten years later all but a very few biologists were agreed on an
evolutionary theory based firmly on Darwin?s own ideas knitted with subsequent
developments in genetics?. (Berry, 1982: 14). 
In the Modern Synthesis account of history, the early Mendelians ?
the ?geneticists? ? are portrayed as naive, foolishly rejecting selection. This
is not correct; what they did do was integrate mutation with selection and deny
that selection was the only directional force in evolution.? For T.H. Morgan (1916, Critique of the theory of evolution) and the other
geneticists, mutation produced the variation while selection pruned off
subviable forms and evolution was a synthesis of the two forces. They saw ?mutation
as the basis of evolution, as the material upon which natural selection works? (Punnett,
1911: 139).??? Morgan (1916) concluded: ?Such a view gives us a somewhat different
picture of the process of evolution from the old idea of a ferocious struggle
between the individuals of a species with the survival of the fittest and the
annihilation of the less fit... New and advantageous characters survive by
incorporating themselves into the race, improving it and opening to it new
opportunities. In other words, the emphasis may be placed less on the
competition between the individuals of a species (because the destruction of
the less fit does not in itself lead to anything that
is new) than on the appearance of new characters and modifications of old
characters that become incorporated in the species...?. 

? MH: you seem to have missed out something here - 'sympatric'?? I think he was correct to dismiss sympatric speciation. Most supposedly sympatric groups actually show high levels of allopatry and the area of sympatry probably represents secondary overlap. The limnetic and benthic forms of three-spined sticklebacks in the British Columbia lakes turned out not to form monophyletic pairs in lakes. Instead, they are related to limnetic and benthic forms, respectively, in other lakes. The two forms didn't evolve by sympatric speciation within a lake but diverged before their secondary overlap (e.g. caused by marine flooding).? 
Cichlids, Rhagoletis pomonella, the? Enchenopa binotata complex...

MH: The same principle applies (especially clear in Rhagoletis). The new work on cichlids (Sparks, Azuma, Genner etc.) suggest they are much older than was thought and?are probably older than the lakes they currently occupy. The same principle applies to the palms of Lord Howe Island, published in Nature?a year or two back as an example of sympatric speciation.

? ?MH: Yes, it was an oversight. Relying on chance to explain spatial patterns in evolution meant that large parts of the modern synthesis were flawed at the outset. (It's not just 'my version' of vicariance - it goes back to Hooker and Huxley and is now used in many publications).?
You mean like Croizat using Kepler as his mirror, his philosophical buddy? 

MH: I'm not sure what you mean.

You cherry-pick to support a case that doesn?t exist. There is no nemesis!

MH: I'm not sure what you mean.

??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?MH: If a mirror is struck by a hammer (vicariance), the individual, broken shards do not move to their current position - they 'evolve' in situ, by the fracturing of a larger entity. ??
So the mirror appeared from nothing? 

MH: The metaphor refers to the origin of the shards, not the mirror. I wasn't talking about the origin of the 'mirror'. The mirror may just be a shard of another 'broken mirror'.?

The pieces do not expand? 

MH: They may or they may not.

No piece is a single population? 

MH: I'm not sure what you mean.

So if I break your mirror over and over I end up with an infinite number of singleton species? 

MH: Yes. That's why a model of evolution has to have phases of overlap (mobilism). If it was just vicariance,?every area would have just one, endemic?species.

Michael the logical fallacies are written all over. 

MH: Where exactly?

Your insistence in only recognizing vicariance 

MH: I've constantly stressed evolution as the interplay between phases of vicariance and phases of range expansion.

pushes your arguments into corners from which the only escape is making illogical arguments or worse, vaguely defined terms 

MH: What terms exactly?

that sound like something else but aren?t unless you have trudged through the Croizat Bible. 

MH: Why do you keep going on about Croizat? 

Just look at your stance on speciation:
?MH: I'd say speciation occurs after the groups are subspecies and before they are subgenera.? 
Don?t you mean populations? 

MH: No.

Why bring in subgenera or subspecies? 

MH: Because subspecies and subgenera are the precursors and 'postcursors' of?species. 

Is it because Croizat can?t work with populations? 

MH: What does Croizat have to do with it? Croizat, like most authors on evolution,?discussed populations countless times. A population that is not differentiated or only very slightly differentiated from the others?would be treated below subspecies rank. A population doesn't usually jump directly to being a species without passing through a phase as 'subspecies'.?So subspecies are more relevant to the question of speciation than are populations.? 

You create a myth that the modern synthesis doesn?t recognise forces other than selection (just Dobzhansky?s papers will put this to rest) 

MH: But in the modern synthesis?selection is the *creative* force.

and then happily parade Croizat????MH: I accept dispersal but not 'chance dispersal'. They accept both and think of them as the same process.?? ??MH: I don't take issue with it. The point is he did not apply this principle in practice, to his analyses of actual groups. This was written in 1976, a couple of years after critique of his work had begun ??to appear in journals such as Syst. Zool. ????MH: I think it defines his ideas in a clear and succinct way. I've read most of what Mayr wrote, including dozens of his early papers.????MH: I'm interested in Mayr only as the source, the type specimen, of the current ideas - most people accept the modern synthesis as basically correct, give or take sympatric speciation, founder effect speciation etc. ??

MH: None of these quotes mention Croizat - how am I 'parading' him? What's the big deal with Croizat?

What is it. I have told you repeatedly that Mayr recognised the influence of both, as have many before and most since have. Yet you call them ?dipersalists?. 

MH: 'Dispersalism'?is a standard term for the Mayrian school, e.g. see Joseph (2008, The changing faces of systematics and biogeography in Australasian ornithology: a young Turks?s view. In W.E. Davis Jr., H.F. Recher, W.E. Boles, and J.A. Jackson (eds.), Contributions to the history of Australasian ornithology (pp. 253-303). Nuttall Ornithology Club, Cambridge, MA).?Joseph?showed
that the most influential research tradition for Australasian ornithology has
been the evolutionary synthesis of Matthew, Simpson and Mayr. In
this approach authors studied ?the colonization of Australia by birds?, and
?Evidently, it was untenable and not worthy of discussion to think that birds
could have been in Australia all along? (Joseph, 2008: 265).?Now molecular work
has shown that the Australasian passerine fauna includes large groups that are
basal in the order and its sub-clades, not unrelated minor offshoots of
northern groups as was assumed, and Joseph concluded that the Australian
passerines are ?as old as the hills?.  

Well, I thank you for your 1982 Mayr article in the Auk, as it was very instructive:
?That there are different causes? for? distributional? discontinuities? was? known and? extensively discussed long? before? Croizat's grandfather was born. Most of? the earlier authors realized? that? there? are? two? kinds? of? discontinuities: (a) primary ones produced by the establishment of a founder population across a geographical barrier, and (b) secondary ones, caused by the disruption of a previously continuous range by a geological event (a fracture of plates, a flooding of shelves, the rise of a mountain range, etc.) or by? a climatic event (ice barrier, origin of savannahs or deserts, etc.)?
Please tell me how vicariance is not mentioned, in equal footing, in this quote. (for those interested the article can be found in this linkhttp://elibrary.unm.edu/sora/Auk/v099n03/p0616-p0622.pdf)

MH: Of course it is?mentioned. But?Mayr's?center of origin/dispersal analyses (and Pleistocene vicariance) were?the standard model for biogeography since the 1940s and for many authors still are. In the quote above,?Joseph?bemoaned?the effect that Mayr's work?had had on Australian ornithology, but Mayr's work had?a similar influence?in many other parts of the world. Whether a biogeographer was working on the fauna of?Winneba or Wewak, he or she?was?supposed?to study the?'colonization' of the area.??Evidently, it was untenable and not worthy of discussion to think that birds could have been in Australia all along?. 

Best
Jason ??? ???  ??? ?  ??? ??? ? 
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