Chapter

Speciation in Amazonia

Edited by Cibele R. Bonvicino and Marcelo Weksler

in Bones, Clones, and Biomes

Published by University of Chicago Press

Published in print June 2012 | ISBN: 9780226649191
Published online February 2013 | e-ISBN: 9780226649214 | DOI: http://dx.doi.org/10.7208/chicago/9780226649214.003.0012
Speciation in Amazonia

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Recent work on the phylogeographic patterns of Amazonian organisms and a better understanding of the geologic history of the region have enabled scientists to specify and test the spatial, temporal, and phylogenetic predictions of these biogeographic models. Four main causal factors have been postulated, and their expectations and predictions are reviewed here: Firstly, the role of rivers as barriers to species dispersal is evident, but their role as primary agents of speciation is still unclear. Secondly, geotectonic changes associated with uplift of the central Andes and increase in global sea levels produced gradual submersion of western Amazonia, creating the wetland system known as Lake Pebas. The effects of marine incursions have been associated with diversification of several organisms, but no mammalian phylogenetic pattern has been effectively linked to Lake Pebas. Thirdly, the genetic structure of rodents and frogs in Western Amazonia is correlated with the location and orientation of the Iquitos Paleoarch, an ancient drainage barrier that survived until the Pliocene. Fourthly, several variations of refugia in response to Quaternary climatic fluctuations are not supported by genetic studies of small mammals. The knowledge of the biogeographic processes leading to patterns within Amazonia is still incomplete, as the mammalian fauna of this vast region and the spatial and temporal genetic patterns of most of its species remain poorly known.

Keywords: organisms; biographic; geotectonic; mammals; Pliocene

Chapter.  8469 words.  Illustrated.

Subjects: Biological Sciences

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