Date: Wed, 10 May 2000 15:08:54 From: SCHLAUER@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1468$foo@default> Subject: Re: Australia's CP diversity
Dear Allen,
> Here in Australia it is a constant puzzle why some genera are "small" in
> the east, but in Western Australia they have diversified spectacularly.
This does quite certainly have climatic reasons. The SW is marked by
etesial, winter rainfall climate, while the SE has subtropical,
summer rainfall climate, caused by the rotation of the earth and the
relative distribution of water and land surface. If we assume that
the ancient Australian stock existed already when the continent
occupied a far more southern geographic position, the pre-
Australian cps were obviously better able to adapt to the transition
from a temperate climate to an etesial one (and to diversify there)
than to a subtropical one.
> The tuberous stuff (subgenus ergaleium) is unique to Aust,
Not really, _D. peltata_ does reach tropical Asia, and its vicariant
_D. insolita_ even occurs in tropical Africa.
> as is subgenus Rorella (with D.pygmaea, D hamiltonii, D.arcturi)
This group is certainly paraphyletic. The species-rich group of
pygmy sundews (subgen. Bryastrum) is likewise not confined to
Australia but its range reaches (with the single species _D. pygmaea_)
Tasmania and New Zealand.
> I would be interested in learned opinion as to where they came from
Both Ergaleium and Bryastrum (and some further, monotypic groups)
originated most probably in Australia (or rather E Gondwana).
> there similar forms in Chile?
The S American _D. uniflora_ does display some features similar to
_D. arcturi_ and especially to _D. stenopetala_. The mutual
relationships are not entirely clear, however.
> how close to Africans eg D. cistiflora.
Quite remote. There are some similarities between _D. arcturi_ and
_D. regia_, a supposedly very primitive species.
> (Note: Many plant families share common ancestry in Gondwana land, which
> split into Aust, Africa, S. America & India at about the time flowers were
> first evolving)
Droseraceae are probably one of the very old families. It did
apparently exist already in the Cretaceous.
> WA also has its own unique CP, Cephalotus follicularis, many Utrics, & 2
> Byblis spp. The east, despite having a much more varied climate &
> geography, has far less variety (NSW 9 drosera, aldrovanda & 7 utrics)
See above.
Kind regards
Jan
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