[Taxacom] PhD studentship on Begonia - Royal Botanic GardenEdinburgh

[John Grehan]

Mark,

Thank you for the note, but your own description about the molecular
data seems to me to show that you have already embedded your approach
within that of dispersalist molecular biogeography - accepting Darwin's
theory that there are centers of origin and that they can be empirically
located by various criteria, and that the molecular clock (which I
presume you use) provides absolute dates of origin (hence the popular
method of separating out 'vicariance' and 'dispersal' according to
whether such dates pre or post date imagined geohistorical events).
Along with that is probably the standard practice of ignoring
biogeographic patterns that might lead to an independently derived
predictions about such origins. Its also interesting to see that Rod
Page is involved as he used to accept the validity of biogeographic
patterns but has since adopted Darwinian dispersalism (under the guise
of molecular approaches) as having invalidated spatial pattern
approaches.

John


 

> -----Original Message-----
> From: Mark Hughes [mailto:M.Hughes at rbge.ac.uk]
> Sent: Friday, September 29, 2006 4:12 AM
> To: John Grehan
> Cc: Roderic Page; taxacom at mailman.nhm.ku.edu
> Subject: RE: [Taxacom] PhD studentship on Begonia - Royal Botanic
> GardenEdinburgh
> 
> Dear John
> I certainly havent ruled out vicariance. The ad was perhaps a little
coy
> in that respect - the full proposal reads
> 
> "...Place the Begonia of Sulawesi in a phylogenetic context, in order
to
> understand the origin of the large number of endemic species on the
> island in terms of tectonic migration, long distance dispersal and
> autochthonous speciation."
> 
> Preliminary (very preliminary) molecular data suggests at least 2
> invasions of Sulawesi by Begonia, with links to the Philippines and to
a
> species complex that is widespread in SE Asia. A quick look at branch
> lengths would suggest that these are only 'recently' diverged and
> probably not vicariant. The deepest split found (albeit in a small
> sample, although quite taxonomically diverse) in Asian Begonia by
Plana
> et al. (2004) was ca. 10 Mya, which may preclude any vicariant events.
> However, we know so little about Sulawesi Begonia (30 names known,
> probably likely to be 3-4 times as many) that I am going to keep an
open
> mind and see what the research tells us.
> 
> Cheers
> 
> Mark.
> Mark Hughes (PhD)
> Begonia Systematist
> Royal Botanic Garden Edinburgh
> Phone: +44 (0)131 248 2893
> Fax: +44 (0)131 248 2901
> 
>
http://www.rbge.org.uk/rbge/web/science/research/conservation/begonia.js
> p
> > -----Original Message-----
> > From: John Grehan [mailto:jgrehan at sciencebuff.org]
> > Sent: 28 September 2006 19:08
> > To: Roderic Page; TAXACOM
> > Cc: Mark Hughes
> > Subject: RE: [Taxacom] PhD studentship on Begonia - Royal Botanic
> > GardenEdinburgh
> >
> >
> > > 2. Explain their origin in terms of dispersal, migration and local
> > > speciation by using molecular phylogenetic techniques.
> >
> > Hmmm - I guess any possibility of vicariant differentiation has
> already
> > been refuted for this group?
> >
> > John Grehan
>