Amazonia and Andes

The hectics of the past month prevented me from making reference to an important review which appeared in November in Science (Hoorn et al., 2010). It is centered around Amazonian geology and Andean uplift, with data on the phylogeny of selected plant and animal groups, on regional climate and on landscape evolution. In total, this review summarizes the current knowledge and gives important clues for further research on the biodiversity of the northern part of South America.

As evidenced by more in-depth papers (Hoorn & Wesselingh, 2010), the paleogeography of northern South America shows a transition from a ‘cratonic’ to an ‘Andean’ dominated landscape during the last 65 million years. 


New data on Andean mountain building and on paleoenvironmental changes in lowland Amazonia, have enabled climatologists to make new models of atmospheric patterns as a result of the orographic changes. In parallel, new insights from DNA research have shed new light on the sequence and approximate timing of diversification of plant and animal groups. 
Western Amazonia has a higher level in nutrient levels in soils, in terrestrial mammal and amphibian richness, and in tree alpha-diversity. This in contrast to the eastern Amazonian Craton, which has fewer species, genera, and families in plant and animal groups. Although this seems paradoxical, as this area had the opportunity to accumulate taxa for a much longer period, the conclusion from the available data is that diversification in western Amazonia must have been particularly rapid.
One of the areas indicated in this review as focus for future research is the transition zone between the Andes and Western (lowland) Amazonia.

Hoorn, C. et al. (17 authors), 2010. Amazonia through time: Andean uplift, climate change, landscape evolution, and biodiversity. – Science 330: 927-931.
Hoorn, C. & Wesselingh, F.P. (eds.), 2010. Amazonia: landscape and species evolution. A look into the past. Wiley, Oxford, xiii+447 pp.

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