[Taxacom] Salvadoraceae paraphyletic? (was: North America...)

[John Grehan]

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
Sent: Thursday, January 05, 2012 9:56 PM

> However, it is perhaps not surprising that it could have 

'could have' is the operative word. It also 'could not have' The question really is about what evidence there is either way. Usually in such matters there is no evidence. The 'could have' or 'could not have' is just made up.


> taken a trip around the
> globe to acquire adaptations to more extreme environments in order to
> eventually reinvade North America and compete with relatives they left
> behind many millions of year earlier.  

But I guess such a scenario 

Yes - its just a story.


> Must be disconcerting to someone who finds it hard to accept dispersal as
> being that important, 

Dispersal is actually very important in biogeography. What is misunderstood here is that dispersal ability and dispersal are two different things. Biogeographic (spatial analysis) indicates hat means of dispersal are more about means of survival and that process is operative in one way (as mobilism) in the generation of an ancestral range, and in another way (as immobilism) in descendant differentiation.

John Grehan
---------------------------------------------              
John Grehan wrote: 
           I am not aware that there is anything
preordained about the number of synapomorphies being required for any
one clade. One is sufficient. Of course it would only take one other
character relationship to make that problematic so it may be regarded as

a 'weak' clade, but then again one character may be all that there is. 



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