Somebody some days ago asked why there are so many Drosera species in
Australia and so few (comparatively) in South America.
Because I call myself a evolutionary plant ecologist, I feel I have to
try to answer the question. It has been nagging me for a while.
There are two possibilities that I have thought of so far.
1) The climate of Australia has been stable over a long time-period.
For South-west Australia for 11 million years. In theory, a stable
environment leads high competition which leads to niche-seperation and
forming of new species. This is also one of the explanations why there
are so many species in the rain forest. The theory is currently under
discussion, because it appears that the rainforest has not been stable
over a long time-period.
2) A species has it's highest genetic variance in the area from where it
originated. The same may hold true for a genus. If Drosera has
originated in Australia, we would expect to find most species in
Australia. However, I don't know from where Drosera has originated.
The genus has a global distribution. Does anyone know from where it has
originated?
Magnus Thor`n
Plantecology, Department of Ecology, Lund University
Ekologihuset, S-223 62 Lund, Sweden
Tel +46-(0)46-109311
Magnus.Thoren@planteco.lu.se
"-You are all different.
-YES, WE ARE ALL DIFFERENT!
-I'm not" (Life of Brian)