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Amazonian Speciation: A Necessarily Complex Model
Mark B. Bush
Journal of Biogeography
Vol. 21, No. 1 (Jan., 1994), pp. 5-17
Published by: Wiley
Stable URL: http://www.jstor.org/stable/2845600
Page Count: 13
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Amazonian speciation will not be explained entirely by any single model of vicariance or climatic change. The refugial hypothesis is rejected in favour of a more complex evolutionary history. Pre-Quaternary vicariance events appear to have established the major regional divisions of species complexes. Quanternary speciation, and the redistribution of existing species, are likely to be superimposed upon this existing pattern, accounting for modern biogeographic patterns. The forcing function driving Quaternary speciation is a combination of glacial age cooling, reduced atmospheric CO2, and moderate reductions in precipitation. It is suggested that the central Amazonian forests did not fragment during glacial times, but that populations within forests without modern analogue were repetedly disrupted by climatic change. The centres of endemism employed to support the concept of unchanging refugia are suggested to have been areas not of maximal stability but of maximal disturbance.
Journal of Biogeography © 1994 Wiley