Palaeo-precipitation is a major determinant of palm species richness patterns across madagascar: A tropical biodiversity hotspot

The distribution of rainforest in many regions across the Earth was strongly affected by Pleistocene ice ages. However, the extent to which these dynamics are still important for modern-day biodiversity patterns within tropical biodiversity hotspots has not been assessed. We employ a comprehensive dataset ofMadagascan palms (Arecaceae) and climate reconstructions from the last glacial maximum (LGM; 21 000 years ago) to assess the relative role of modern environment and LGMclimate in explaining geographical species richness patterns in this major tropical biodiversity hotspot. We found that palaeoclimate exerted a strong influence on palmspecies richness patterns,with richness peaking in areas with higher LGM precipitation relative to present-day even after controlling for modern environment, in particular in northeasternMadagascar, consistent with the persistence of tropical rainforest during the LGM primarily in this region.Our results provide evidence that diversity patterns in theWorld's most biodiverse regions may be shaped by long-term climate history as well as contemporary environment. & 2013 The Author(s) Published by the Royal Society. All rights reserved.