A CHEMICAL AND MORPHOLOGICAL STUDY OF NITRARIA (NITRARIACEAE) POLLEN, WITH IMPLICATIONS FOR HISTORICAL BIOGEOGRAPHY

International audienceThe steppe-desert taxon Nitraria (Nitrariaceae) is thought to haveoriginated in the Tibetan highlands in the Paleogene, from whereit dispersed to coastal regions in the Mediterranean, Middle Eastand Southern Australia. Nitraria is an ideal genus for inferring thehistorical Tibetan steppe development, yet much of its evolutionremains unknown. We investigated whether pollen morphologyand chemical composition of the exine are useful in separatingspecies and informing on the historical biogeography of Nitraria.We also tested whether pollen characteristics relate to a particulargeographic region. To achieve these goals we used a novel approachconsisting of a combination of classical pollen morphologicalanalysis with Light Microscopy (LM) and Scanning ElectronMicroscopy (SEM), Fourier Transformed Infrared spectroscopy(FTIR) and molecular phylogenetics. We found that this integrationof data types provides a powerful tool for exploring the evolutionaryhistory of Nitraria. Multivariate approaches could be usefulfor assigning fossil specimens to modern taxa. These results willnow be used to reconstruct the historical biogeography of Nitraria