The evolutionary history of the Central Asian steppe-desert taxon <i>Nitraria</i> (Nitrariaceae) as revealed by integration of fossil pollen morphology and molecular data

Abstract The transition from a greenhouse to an icehouse world at the Eocene-Oligocene Transition (EOT) coincided with large decrease of pollen steppe-adapted genus Nitraria. This genus, now common along Mediterranean coast, Asia and Australia, has proposed coastal origin geographically widespread fossil record. Here we investigated evolution, taxonomic diversity morphological disparity Nitraria throughout Cenozoic by integrating extant taxa palynological morphotypes into unified phylogenetic framework based on both DNA sequences data. We present oldest grain Nitraria, least 53 Myr old. was found in Central Asian deposits, providing new evidence for its this area. that EOT is evolutionary bottleneck coinciding retreat proto-Paratethys Sea, major global cooling event turnover steppe vegetation. infer crown age modern spp. be significantly younger (Miocene) than previously estimated (Palaeocene). trajectory inferred extant-only differs markedly one also considers extinct taxa. Our study demonstrates it therefore critical apply integrative approach fully understand plant history Nitrariaceae.