[Taxacom] Seed plants of Fiji
jgrehan at sciencebuff.org
Thu Nov 16 21:06:02 CST 2006
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Karl Magnacca
In many cases of hypothesized vicariance, the barrier is hypothetical.
In this case, it's because you're talking about terrestrial organisms
that cannot survive in the sea crossing 1000+ miles of ocean and landing
on a tiny speck of land.
Quite right - hypothetical. My point.
What makes you think Metrosideros is vicariant rather than dispersed?
It produces millions of tiny wind-dispersed seeds, so absent other
evidence trans-oceanic dispersal seems much more likely.
If you take a look at the distributions you will see that they are
vicariant. It's an obvious enough pattern. You do know what a vicariant
> I am referring to vicariant form-making.
If you don't know it would appear you have not read much biogeographic
literature. It's a well established term (except that it is probably
ignored by dispersalist biogeography). Read Craw et al 1999.
> All of this is nice theory,
I'm just talking about the definition of the word "vicariance", it has
nothing to do with theory.
It does since you were using it in the context of a theorized process.
> Mobilism within vicariant ranges maintains the existence of the taxon
> without obliterating the underlying vicariism.
Mobilism on that scale across hundreds of miles of ocean = not bloody
Perhaps, perhaps not.
> No - just did not leave behind a stratigraphic trace as the current
> site of the islands, just as there is no trace left at the Galapagos
> even though many geologists accept the possibility of a former island
> arc connection.
It looks to me like there is a ridge that extends from the Galapagos to
South America. If you're saying there's just no trace at the "current
site of the islands", you need to explain a) how the islands got to
where they are, and b) how the seafloor around them got smoothed out.
Geologists have already done that.
> They neither help nor hinder if one accepts that biogeography
> constitutes an independent research program with its own methods and
> principles. That is true of panbiogeography, but it may not be true of
> all other methods. There are geologists who have suggested such
> structures as I have talked about, but you wont see them by just
> looking at a map of the Pacific.
But when you have a system that produces conclusions that another area
of science says is impossible,
Geology does not say that the panbiogeographic model for the Pacific is
Nothing you've said has actually challenged standard geology, just that
your conclusions say the geology is wrong, therefore it must be.
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