[Taxacom] Two primitive mammals in one week

[John Grehan]

The essay basically claims that molecular clocks provide empirical
evidence of divergence and therefore demonstrate that a lot of NZ
organisms postdate its geological isolation. Unfortunately, even though
molecular systematists get away with this claim, it is not true. They
ignore that fact that that there are biogeographic and geological models
whereby so-called "oceanic islands" such as the Galapagos and Fiji may
have inherited older biota through mobile island arcs etc. The
panbiogeographic evidence for divergence estimates of the NZ biota are
ignored completely in the essay. Also ignored is the fact that
panbiogeographic analysis is not based on the peculiar composition of
the biota (it isn't really any more peculiar than anywhere else) and a
limited interpretation of the geology. The authors got a carte blanc on
this one.

 John Grehan

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Geoff Read
Sent: Thursday, December 14, 2006 10:05 PM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Two primitive mammals in one week

Ken Kinman wrote:
>     The other is particularly interesting biogeographically (as well 
> as ecologically), being a non-volant mammal from the Miocene of New 
> Zealand.  It also is a primitive mammal, splitting off not far from 
> multituberculates, so it too has its origins in the Mesozoic.  Was it 
> climate change that forced such mammals into extinction in New 
> Zealand, or what it something else?

Like drowning when that part of NZ submerged?  It is described from
fragments so one immediate thought I had was that it was really a bat,
but the authors deal to that idea.

Also out today on the topic of NZ biogeography is an essay which looks
interesting:

Trewick SA, Paterson AM, Campbell HJ 2007. Hello New Zealand. Journal of
Biogeography 34(1): 1-6.

Abstract: " Islands of the Pacific Ocean have long fascinated
evolutionists. Oceanic islands, generally the products of volcanic
activity, provide natural experiments as biological populations are well
delimited and the age of islands can be determined using radiometric
dating. 'Continental islands', including New Caledonia and New Zealand,
provide equally valuable opportunities for evolutionary study. For
students of New Zealand biogeography, the peculiar composition of the
biota coupled with a limited interpretation of geology has resulted in
the widespread acceptance that the flora and fauna is primarily ancient
and of vicariant Gondwanan origin. There is increasing evidence from
molecular data that much of this biodiversity is the product of
evolution following relatively recent colonization. Such data have
prompted biologists to consider geological information on New Zealand in
more detail. At the heart of the issue is the question of whether modern
New Zealand has a terrestrial link through time with the continent
Zealandia that split from Gondwanaland some 80 Ma. Zealandia, which
includes New Caledonia, Lord Howe Island and several of the subantarctic
islands, is now largely submerged, and New Zealand's present terrestrial
existence is the product of tectonic activity initiated around 26 Ma. We
argue that for the purposes of biogeographical interpretation, New
Zealand can be treated as an oceanic island."


Geoff
-- 
   Geoff Read <g.read at niwa.co.nz>
    http://www.annelida.net/
    http://www.niwascience.co.nz/ncabb/



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