Date: Wed, 10 May 2000 21:10:05 +0000 From: schlauer@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg1475$foo@default> Subject: re: Oldest CP
Dear Ivan,
> Brilliant! but you seem to have missed some of my points Jan,
I don't think so (cf. the rest of my reply that you truncated).
> this is a very complicated matter.
Yes, indeed. And most of it is guesswork.
> Of course the Scrophulariales are young, but
> when did the line achieve carnivory?
Very difficult to tell. There is no good fossil evidence for
carnivory whatsoever. It can, however, be assumed that at least
_Utricularia_ did have its characteristic traps when it first
appeared as an independent genus (because it is difficult to imagine
that such complex organs should have developed several times
convergently).
> All agree that the family
> Lentibulariaceae has the most diversity in regard to trapping mechanism.
> Ranging from butterworts, having the most simple trap ( since it is much
> like a nonCP, example -Martynia ), to bladderworts which have the most
> complex. Does not this diversity suggest a longer time period to develop,
> hence an older age?
Not necessarily. In fact the extreme extrapolation of your statement
would be that _Utricularia_ must be the oldest genus of
Lentibulariaceae because it has the most complicated traps, which
must have taken the longest time to develop. But all remaining
evidence we have indicates that _Utricularia_ is actually the
*youngest* genus in the family that emerged only *after* the division
between _Pinguicula_ and _Genlisea_, possibly from a branch closer to
what is now _Genlisea_. So in spite of its tremendous number of
species, _Utricularia_ did have the shortest time of all genera in
Lentibulariaceae (and possibly even of all cp genera) to develop this
diversity!
> Pollen of Nepenthes and Lentibulariaceae only appear later during the
> Miocene (23-5 MYA).
But seeds of Droseraceae (which belong to the very same order
Nepenthales) appear in the Cretaceous.
> In the above you state that that Byblis is apparently
> a Scrophularialean, as of course we know Lentibulariaceae are also. Now
> consider this, by linking Byblidaceae to Lentibulariaceae a clear already
> organized pattern emerges of a lineage running easily back to the time of
> the dinosaurs.
But there is no fossil evidence for this.
> The Byblidaceae are placed in the Pittosporales.
This is the problematic point. Pittosporales are far away from
Scrophulariales. They belong to a clade also containing Araliales and
Asterales. Scrophulariales do belong to a different clade that
contains Solanales and Gentianales. In this latter clade,
Scrophulariales (with the possible exception of Oleaceae) constitute
a comparably young order, of which most families arose in the
Tertiary (after all dinosaurs).
> For much
> literature citings see Origins of the Genus Byblis, DeGreef, CPN Sept &
> Dec 1990.
All these are old data that could not take the more recent genetical
(since Albert & al., 1992) and phytochemical findings (Budzianowski,
1997) into account. But these latter are quite compelling
(Byblidaceae do *not* belong to Pittosporales).
> How did the Pittosporales reach Australia?
This is immaterial here because Pittosporales do not have much in
common with any cps (v.s.)
> They are believed to
> have migrated during the mid-Cretaceous (90 MYA). But the line is traced
> back still further! Ancestors of the order identified in two pollen finds
> from the U.S.A., are dated 100-90 MYA.
Nice but off topic (v.s.).
> I am aware of the fossil evidence we have of possible Aldrovanda
> leaves,-missing important features, and Aldrovanda-like seed, also
> Dionaea-like Fisheropolis pollen. My feelings are, take what fossil
> evidence we have with a grain of salt. In Lloyd's book is mentioned
> fossil bladderwort; most likely erroneous data. I rely on the more
> concrete evidence we have in the study now living plants. As I mentioned
> above, Lentibulareaceae shows the greatest diversity which suggests it to
> be of the oldest CP line.
As I mentioned above, it is the probably youngest line
(_Utricularia_) that contains the most species. There are other cases
of rapid speciation in young genera (e.g. in Asteraceae or
Orchidaceae). Species numbers alone (i.e. without a corresponding
phylogenetic theory) are not indicative of old age (cf. _Ginkgo_ with
only one surviving species, which is certainly much older than all
cps). According to your theory, dinosaurs or possibly even Trilobites
would have to be the largest group of animals now.
Species numbers can, however, indicate centres of origin or of
secondary diversification.
> The scant fossil evidence supports this as well.
I fear I do not entirely understand what you mean here.
Kind regards
Jan
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