Drosera evolution (part 1)

Fernando Rivadavia Lopes (ferndriv@cat.cce.usp.br)
Tue, 6 Jun 1995 11:12:25 -0300 (EST)


This is my 4th attempt at answering your fantastic reply on my
Drosera evolution question, the last 3 were unexplicably erased just as
I was proofreading each (after wasting around 2 or 3 hours writing
each). Maybe it had to do with the length of the reply. I'll try to
write and send this reply in parts now, so as to not add to the
approximately 8 hours already spent on it.
First I'd like to comment on what you said about flowering of
Australian Drosera. Though the species usually seem to produce few seeds,
I believe the flowers MUST carry out a very important role for those
species or else they wouldn't have developed such morphologically diverse
flowers, comparing to the Brazilian Drosera at least (which are
practically all extremely similar).
It could simply be that the few seeds produced are a result of
pollen auto-incompatibility, which (if it exists) would probably be very
high if you consider those populations of pygmy or tuberous sundews which
might often originate from a few clones through vegetative reproduction.
Or the various species could also be saving energy and not producing
excess seeds, the small amount observed being necessary to maintain a
good gene flow in each population. Or it could also be that large
quantities of seeds might not be necessary if the probability of
germinating successfully is high. This might very well be true if you
consider the apparently low competition from other plant species faced
by Drosera in their sandy habitats in Western Australia.

Sao Paulo, Brazil