‘CLAMP Online’: a new web-based palaeoclimate tool and its application to the terrestrial Paleogene and Neogene of North America

CLAMP Online is a new form-driven web facility enabling Climate Leaf Analysis Multivariate Program (CLAMP) palaeoclimate determinations to be conducted in their entirety without the need for additional software. This facility is demonstrated using physiognomic data from 82 Eocene to Pliocene fossil sites in North America, the Physg3brc CLAMP calibration file, and both locally derived climate data (Met3br) and 0.5° × 0.5° gridded climate data (GRIDMet3br). All the fossil sites fall within the physiog- nomic space defined by the Physg3brc dataset showing the versatility of this calibration for Paleogene to Present sites in North America. The fossil sites also plot in the mesic part of physiognomic space confirming that the source of the fossil material was vegetation growing under conditions where water was not growth-limiting to any significant degree. Regression equations are derived relating the local to the gridded climate predictions showing the relative predictive capabilities of each dataset, as well as offering ways to convert previously published data between the two calibrations. Palaeoclimate data (mean annual, warm month mean and cold month mean temperatures, growing season length, growing season and mean monthly growing season precipitation, precipitation during the three consecutive wettest and three consecutive driest months, and annual averages for relative and specific humidities and enthalpy) are given for all 82 sites

Recently evolved diversity and convergent radiations of rainforest mahoganies (Meliaceae) shed new light on the origins of rainforest hyperdiversity

Tropical rainforest hyperdiversity is often suggested to have evolved over a long time-span (the ‘museum’ model), but there is also evidence for recent rainforest radiations. The mahoganies (Meliaceae) are a prominent plant group in lowland tropical rainforests world-wide but also occur in all other tropical ecosystems. We investigated whether rainforest diversity in Meliaceae has accumulated over a long time or has more recently evolved. We inferred the largest time-calibrated phylogeny for the family to date, reconstructed ancestral states for habitat and deciduousness, estimated diversification rates and modeled potential shifts in macro-evolutionary processes using a recently developed Bayesian method. The ancestral Meliaceae is reconstructed as a deciduous species that inhabited seasonal habitats. Rainforest clades have diversified from the Late Oligocene or Early Miocene onwards. Two contemporaneous Amazonian clades have converged on similar ecologies and high speciation rates. Most species-level diversity of Meliaceae in rainforest is recent. Other studies have found steady accumulation of lineages, but the large majority of plant species diversity in rainforests is recent, suggesting (episodic) species turnover. Rainforest hyperdiversity may best be explained by recent radiations from a large stock of higher level taxa