Research on distribution pattern of Subg. Salvia Benth.( Lamiaceae),an important group of medicinal plants in East Asia

The Subg. Salvia Benth. is the largest subgenus in the Salvia Linn. and is native to China. Most of the 44 species and 13 varieties in the subgenus contain active compounds and have medicinal effects similar to that of Salvia miltiorrhiza,and thus serves as a wild resource with relatively high prospects as medicinal plants. Morphological investigation shows that Subg. Salvia exhibits the original characteristics of the Salvia as well as notable species differentiation,and so it is an important group for studying the origin and evolution of the Salvia. Geographically,this subgenus is mainly distributed in higher elevation areas in the Tibetan Plateau and Hengduan Mountains,nevertheless a few extending to central and east China. Hence,intense pressure exists to protect this resource due to the subgenus is vulnerable to environmental,global climate change and disturbance of human activities. Based on aforementioned factors and combined with specimen records,documented 2689 species distribution records with latitude and longitude information,and 1007 records with elevation information,covering 286 county-level regions,a comprehensive survey of Subg. Salvia was conducted and their distribution map was plotted. Furthermore,their distribution pattern was analyzed on the level and vertical dimensions at the differentsections and series in the subgenus. The potential distribution regions with Subg. Salvia were predicted using maximum entropy ecological niche modelling( Maxent). In addition,dominant climatic factors affecting its present distribution were confirmed. The results showed that the Hengduan Mountains serves as the diversity center of this subgenus; its distribution range is from southeastern Tibet to western Sichuan,rarely spreading to northern Hebei and eastern Hubei. In this subgenus,narrow-ranging endemic species have a very high proportion( 45% of all species). In addition,the six series within the subgenus show a vicarious distribution as related to elevation,gradual transitioning from the narrow-ranging species of high elevation to wide-ranging species of low elevation. The subgenus potential distribution obtained based on a maximum entropy model was mostly consistent with the actual distribution of the species. Regarding the relationship between single climatic factors and probability of occurrence, the amount of precipitation of September and December, the temperature annual range,altitude,maximum temperature of March and temperature seasonality are the dominant climate factors influencing species distribution. In view of a key innovation for Salvia speciation,stamen differentiation was investigated in this study. The results showed that the filament to connective ratios of the stamen of Subsect. Annuae,Ser.Campanulatae and Ser. Maximowiczianae,of which the distributions spread to low-elevation areas,are far smaller than Ser.Hiantes,Ser. Digitaloidites and Ser. Brachylomae,of which the distributions are concentrated in high-elevation areas in the southwest; thus the former may be more evolutionary advanced than the latter. Environmental and climatic factors and pollinator choice may together determine the current distribution pattern of the Subg. Salvia.