Detecting the richness and dissimilarity patterns of Theaceae species in southern China

Theaceae is a plant family that mainly distributed in tropical or subtropical regions of Asia. Most species of Theaceae are endemic to China. Here, we used the herbarium collections aim to: a) detect the spatial species richness patterns; b) find out the geographical divisions and c) detect the environmental drivers of the dissimilarity patterns (β diversity). The current distributions of 193 Theaceae species were modeled using MaxEnt. Meanwhile, we calculated the pair wise dissimilarity between grid cell assemblages based on beta-sim index. An ordination was used to analyze the environmental drivers of the dissimilarity patterns. We found that the diversity hotspots for Theaceae species mainly locate in Fujian and Guangxi province. Two major divisions were suggested by the ordination analysis. The longitudinal division implies the climatic divergences between southeastern and southwestern China, while the latitudinal division implies the geographical barriers. For the species in southeastern China, the dissimilarity pattern is mainly driven by temperature annual range, annual precipitation and annual mean temperature. In the southwestern China, isothermality, precipitation seasonality and the rising altitude are the three main drivers. For effective conserving the Theaceae species, the protection of the micro-habitats and the high diversity areas on both sides of these divisions will be essential.