[Taxacom] Hypothesis: How Nothofagus rafted to New Zealand
jgrehan at sciencebuff.org
Sun Dec 24 10:52:01 CST 2006
John Grehan's responses in quotes
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Ken Kinman
Sent: Saturday, December 23, 2006 11:03 PM
To: taxacom at mailman.nhm.ku.edu
Cc: biogeography at bohm.snv.jussieu.fr
Subject: [Taxacom] Hypothesis: How Nothofagus rafted to New Zealand
Now back to dispersal (sorry for the rant against panbiogeographers who overdo the vicariance thing, but Grehan really provoked me this time and was asking for it in my opinion; I'm tired of being called a Darwinian
dispersalist when I recognize lots of vicariance too).
"But Darwin also recognized vicariance. Recognizing vicariance does not exclude one from being a Darwinian dispersalist. I am sorry that I cannot find any other more accurate label for Ken's position, but he uses the two principle methodological tools of Darwinian dispersalism - centers of origin, means of dispersal. It does not matter whether these concepts are applied before or after the appearance of a barrier - its still Darwinian dispersalism."
[various dispersal scenarios excerpted]...... The same rafting mechanism could have taken Nothofagus gunnii to New Zealand to found the truncata-fusca-solandri group (all four form a clade in subgenus Fuscospora). Or maybe a bird could have done this as well, since these species apparently have no Cyttaria fungi associated with them (although one could perhaps even imagine a bird eating both Nothofagus cunninghamii seeds and Cyttaria spores before taking off for--or being blown to--New Zealand). Next I need to look into mosses and insects which may be (like Cyttaria) unique to Nothofagus. No telling what all a floating tree could have carried over with it, and I need all the evidence I can in order to get Grehan off my back. But enough for one day. I'm tired.
"Once can imagine any, possibly infinite 'maybes'. Maybe the moas and kiwis swam across the Tasman, or they hitched a ride on a Nothofagus raft. Maybe the native frog ancestor found a large salt-protected southbound raft from Vancouver (this was actually proposed by one frog specialist based on a molecular clock divergence estimate of 40 Ma). Maybe a pregnant tuatara hung onto the foot of a large bird that was eager to get to New Zealand in a hurry. Maybe this, maybe that. Maybes seem to be a very poor way to do science. But maybe I am wrong on that. I thought, perhaps wrongly, that the purpose of Lists were for dissemination of information and discussion. If Ken or others wish to propose on TAXACOM that molecular clocks refute panbiogeographic evidence I would be the last to object. But I am going to challenge assertions, just as others may (and have) challenged mine. If Ken finds it tiresome to have to defend his beliefs and wants me off his back, then the best thing is not to state the beliefs on the list. Otherwise I am always happy to cordially discuss differences, regardless of whether agreement is reached."
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