Tracing the Origin and Diversification of Dipodoidea (Order: Rodentia): Evidence from Fossil Record and Molecular Phylogeny

Dipodoidea are a diverse rodent group whose earliest known record is from the Middle Eocene. The evolution and diversification of this superfamily have been documented by fossils and comparative morphology, but have not yet been studied from the perspective of molecular phylogeny. This study is the first attempt to reconstruct an extensive phylogeny of Dipodidae and estimate divergence times based on a nuclear gene coding for interphotoreceptor retinoid-binding protein. We found that there is a wide measure of agreement with the fossil record. Each of the three ecological groups of the extant Dipodoidea (sicistines, zapodines, and jerboas) has its distinctive distribution; the distribution patterns have been shaped by the dispersal events. The key events of paleogeographic distribution coincided with major paleoenvironmental events in the Cenozoic. The first important diversification phase occurred during the period from the Oligocene to Early Miocene, when global climate underwent major changes beginning with the Eocene/Oligocene boundary. The second adaptive radiation occurred within jerboas and was associated with the expansion of open habitat starting with the late Middle Miocene. The diversification of jerboas can be correlated with habitat changes in response to global and regional climatic events.