Major Radiations in the Evolution of Caviid Rodents: Reconciling Fossils, Ghost Lineages, and Relaxed Molecular Clocks

PEREZ, M.E.; POL, D.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2012 vol. 7 p. 1 - 21

1932-6203

Background: Caviidae is a diverse group of caviomorph rodents that is broadly distributed in South America and is dividedinto three highly divergent extant lineages: Caviinae (cavies), Dolichotinae (maras), and Hydrochoerinae (capybaras). Thefossil record of Caviidae is only abundant and diverse since the late Miocene. Caviids belongs to Cavioidea sensu stricto(Cavioidea s.s.) that also includes a diverse assemblage of extinct taxa recorded from the late Oligocene to the middleMiocene of South America (??eocardiids??).Results: A phylogenetic analysis combining morphological and molecular data is presented here, evaluating the time ofdiversification of selected nodes based on the calibration of phylogenetic trees with fossil taxa and the use of relaxedmolecular clocks. This analysis reveals three major phases of diversification in the evolutionary history of Cavioidea s.s. Thefirst two phases involve two successive radiations of extinct lineages that occurred during the late Oligocene and the earlyMiocene. The third phase consists of the diversification of Caviidae. The initial split of caviids is dated as middle Miocene bythe fossil record. This date falls within the 95% higher probability distribution estimated by the relaxed Bayesian molecularclock, although the mean age estimate ages are 3.5 to 7 Myr older. The initial split of caviids is followed by an obscureperiod of poor fossil record (refered here as the Mayoan gap) and then by the appearance of highly differentiated modernlineages of caviids, which evidentially occurred at the late Miocene as indicated by both the fossil record and molecularclock estimates.Conclusions: The integrated approach used here allowed us identifying the agreements and discrepancies of the fossilrecord and molecular clock estimates on the timing of the major events in cavioid evolution, revealing evolutionary patternsthat would not have been possible to gather using only molecular or paleontological data alone.