Landscape diversity patterns and endemism of Araceae in Ecuador

Araceae is one of the largest herb families in tropical America, but its patterns of diversity and endemism are poorly known. We used predictive distribution modelling in GIS to study Araceae richness on a landscape scale in Ecuador. Modelling was based on georeferenced herbarium collections with humidity and mean annual temperature as climatic variables. Variation partitioning using multiple regression showed that humidity and altitude were main factors in explaining Araceae diversity patterns. Endemism was less well explained by present climatic factors. Unlike common diversity patterns of herbs or epiphytes, Araceae richness was highest in the eastern (Amazon) lowland rain forest with a secondary centre on the Andean foothills of northwestern Ecuador. The peak in endemism was on the western slopes of the Andes, corresponding to areas that have been severely affected by human activities and deforestation. Eastern lowland (Amazonian) forests were poor in endemic Araceae.