Karst ecosystems in southern China are species-rich and have high levels of endemism,yet little is known regarding the evolutionary processes responsible for the origin and diversification of karst biodiversity. Dr. Hanghui Kong et al. from the Plant Genetic Resources and Evolution Lab, South China Botanical Garden, reconstructed the phylogeny of the speciose genusPrimulinaby using multiple molecular data. Then they assessed the effects of past climatic changes on species diversification and evolutionary history ofPrimulina, a typical karst plant in southern China. They found that speciation was positively associated with changes in past temperatures and East Asian monsoons through the evolutionary history ofPrimulina. Climatic change around the mid-Miocene triggered an early burst followed by a slowdown of diversification rate towards the present with the climate cooling. They detected different speciation rates among edaphic types, and transitions among soil types were infrequently and did not impact the overall speciation rate.These findings suggest that both global temperature changes and East Asian monsoons have played crucial roles in floristic diversification within the karst ecosystems in southern China, such that speciation was higher when climate was warmer and wetter. This is the first study to directly demonstrate thatpast monsoon activity is positively correlated with speciation rate in East Asia. This study could motivate further investigations to assess the impacts of past environmental changes on the origin and diversification of biodiversity in global karst ecosystems, most of which are under threat.

This work was funded by grants from the Natural Science Foundation of China- Guangdong Natural Science Foundation Joint Project (U1501211) and Southeast Asia Biodiversity Research Institute, Chinese Academy of Science (Y4ZK111B01). The results have been published in Molecular Ecology (http://onlinelibrary.wiley.com/doi/10.1111/mec.14367/full).

Fig. 1 Representative Primulina species in karst ecosystem.

Fig. 2 Bayesian analysis of macrevolutionary mixtures in Primulina.

Fig. 3 Diversification pattern of Primulina based on past fluctuations of temperatures and East Asian monsoons from the mid-Miocene.