02376nas a2200145   4500008004100000245020200041210006900243260002000312300001200332490000700344520176800351100002502119700002302144856006302167       2011                        eng d00aMass Extinction, Gradual Cooling, or Rapid Radiation? Reconstructing the Spatiotemporal Evolution of the Ancient Angiosperm Genus Hedyosmum (Chloranthaceae) Using Empirical and Simulated Approaches0 aMass Extinction Gradual Cooling or Rapid Radiation Reconstructin  cOctober 1, 2011  a596-6150 v603 aChloranthaceae is a small family of flowering plants (65 species) with an extensive fossil record extending back to the Early Cretaceous. Within Chloranthaceae, Hedyosmum is remarkable because of its disjunct distribution–1 species in the Paleotropics and 44 confined to the Neotropics–and a long "temporal gap" between its stem age (Early Cretaceous) and the beginning of the extant radiation (late Cenozoic). Is this gap real, reflecting low diversification and a recent radiation, or the signature of extinction? Here we use paleontological data, relaxed-clock molecular dating, diversification analyses, and parametric ancestral area reconstruction to investigate the timing, tempo, and mode of diversification in Hedyosmum. Our results, based on analyses of plastid and nuclear sequences for 40 species, suggest that the ancestor of Chloranthaceae and the Hedyosmum stem lineages were widespread in the Holarctic in the Late Cretaceous. High extinction rates, possibly associated with Cenozoic climatic fluctuations, may have been responsible for the low extant diversity of the family. Crown group Hedyosmum originated c. 36–43 Ma and colonized South America from the north during the Early-Middle Miocene (c. 20 Ma). This coincided with an increase in diversification rates, probably triggered by the uplift of the Northern Andes from the Mid-Miocene onward. This study illustrates the advantages of combining paleontological, phylogenetic, and biogeographic data to reconstruct the spatiotemporal evolution of an ancient lineage, for which the extant diversity is only a remnant of past radiations. It also shows the difficulties of inferring patterns of lineage diversification when incomplete taxon sampling is combined with high extinction rates.1 aAntonelli, Alexandre1 aSanmartín, Isabel  uhttp://sysbio.oxfordjournals.org/content/60/5/596.abstract02093nas a2200169   4500008004100000245007500041210006900116260001800185300001400203490000800217520155100225100002501776700002701801700001901828700002301847856005301870       2009                        eng d00aTracing the impact of the Andean uplift on Neotropical plant evolution0 aTracing the impact of the Andean uplift on Neotropical plant evo  cJune 16, 2009  a9749-97540 v1063 aRecent phylogenetic studies have revealed the major role played by the uplift of the Andes in the extraordinary diversification of the Neotropical flora. These studies, however, have typically considered the Andean uplift as a single, time-limited event fostering the evolution of highland elements. This contrasts with geological reconstructions indicating that the uplift occurred in discrete periods from west to east and that it affected different regions at different times. We introduce an approach for integrating Andean tectonics with biogeographic reconstructions of Neotropical plants, using the coffee family (Rubiaceae) as a model group. The distribution of this family spans highland and montane habitats as well as tropical lowlands of Central and South America, thus offering a unique opportunity to study the influence of the Andean uplift on the entire Neotropical flora. Our results suggest that the Rubiaceae originated in the Paleotropics and used the boreotropical connection to reach South America. The biogeographic patterns found corroborate the existence of a long-lasting dispersal barrier between the Northern and Central Andes, the "Western Andean Portal". The uplift of the Eastern Cordillera ended this barrier, allowing dispersal of boreotropical lineages to the South, but gave rise to a huge wetland system ("Lake Pebas") in western Amazonia that prevented in situ speciation and floristic dispersal between the Andes and Amazonia for at least 6 million years. Here, we provide evidence of these events in plants.1 aAntonelli, Alexandre1 aNylander, Johan, A. A.1 aPersson, Claes1 aSanmartín, Isabel  uhttp://www.pnas.org/content/106/24/9749.abstract