Sem essa de estase na fauna primata da América do Sul

quarta-feira, março 25, 2009

Successive radiations, not stasis, in the South American primate fauna

Jason A. Hodgsona, Kirstin N. Sternera, Luke J. Matthewsa, Andrew S. Burrella, Rachana A. Jania, Ryan L. Raaumb,c,Caro-Beth Stewartd, and Todd R. Disotella,1

aCenter for the Study of Human Origins, Department of Anthropology, New York University, New York, NY 10003; bDepartment of Anthropology, Lehman College, Bronx, NY 10468; cThe Graduate Center, City University of New York, New York, NY 10016; and dDepartment of Biological Sciences, State University of New York, Albany, NY 12222

Edited by Morris Goodman, Wayne State University, School of Medicine, Detroit, MI, and approved February 18, 2009 (received for review October 16, 2008)


The earliest Neotropical primate fossils complete enough for taxonomic assessment, Dolichocebus, Tremacebus, and Chilecebus, date to approximately 20 Ma. These have been interpreted as either closely related to extant forms or as extinct stem lineages. The former hypothesis of morphological stasis requires most living platyrrhine genera to have diverged before 20 Ma. To test this hypothesis, we collected new complete mitochondrial genomes from Aotus lemurinus, Saimiri sciureus, Saguinus oedipus, Ateles belzebuth, and Callicebus donacophilus. We combined these with published sequences from Cebus albifrons and other primates to infer the mitochondrial phylogeny. We found support for a cebid/atelid clade to the exclusion of the pitheciids. Then, using Bayesian methods and well-supported fossil calibration constraints, we estimated that the platyrrhine most recent common ancestor (MRCA) dates to 19.5 Ma, with all major lineages diverging by 14.3 Ma. Next, we estimated catarrhine divergence dates on the basis of platyrrhine divergence scenarios and found that only a platyrrhine MRCA less than 21 Ma is concordant with the catarrhine fossil record. Finally, we calculated that 33% more change in the rate of evolution is required for platyrrhine divergences consistent with the morphologic stasis hypothesis than for a more recent radiation. We conclude that Dolichocebus, Tremacebus, and Chilecebus are likely too old to be crown platyrrhines, suggesting they were part of an extinct early radiation. We note that the crown platyrrhine
radiation was concomitant with the radiation of 2 South American xenarthran lineages and follows a global temperature peak and tectonic activity in the Andes.

Kewywords mitochondrial phylogeny _ molecular clock _ New World monkeys _
primate evolution _ platyrrhine origins

PDF do artigo gratuito aqui.