Biogeography of Plants in Western Amazonia

[Holger Kreft]

john grehan wrote:

> Another consideration may be that these species may have gone the other
> direction. That some 'slide' up through tectonic uplift. It would be
> interesting (to me at least) to know how the distribution maps led
> necessarily to the conclusion of sliding down. In the New Guinea
> mountains
> there are cases of same species and related species connections between
> alpine or upland and the lowlands that appear to be correlated with
> tectonic uplift.

- The point why I came to the conclusion that species seem to slide down
is that the following.
A number of species show a wide distribution from the Central American
Cordilleras down South to the Bolivian Andes. In this range they show a
more or less strikt montane distribution with the centre in montane
cloud forests between 1500-2000 m a.s.l. Only in the very humid parts of
Western Amazonia these species also occur in the lowlands. Would the
"slide up" effect like you mentioned in the context of Andean uplift be
an appropriate interpretation of this pattern?
Since the Andean (and Amazonian) climate history of the Ecuadorian part
of the East Andes is quite complex I could imagine that during
Pleisocene climatic fluctuations when vegetation belts were pressed
downwards a number of species could have survived in these lowland
forest refugia (so I mean not only lowland taxa as described by various
authors, but also montane taxa). That would mean that the pattern I have
described is more a picture of Pleistocene climate than of tectonic uplift.

Holger Kreft


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Dipl. Biol. Holger Kreft
Botanical Institut and Botanical Garden
University of Bonn
Meckenheimer Allee 170
D-53115 Bonn, Germany
++49-(0)-228-73-6333
hk at uni-bonn.de
http://www.botanik.uni-bonn.de/system/epiphyt.htm
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