中国弧隔鼠尾草亚属(唇形科)的分布格局

弧隔鼠尾草亚属(Subg.Salvia Benth.)是中国原产鼠尾草属最大的属下类群,有44种13变种,大多含有与丹参(S.miltiorrhiza)类似的活性化合物成分和药用功效,是具有较高利用前景的野生药用植物资源。从形态学分析,该亚属具备原始类群的主要特征,物种分化明显,是研究鼠尾草属起源和演化的关键材料;从地理分布格局看,该亚属集中分布于青藏高原以及横断山脉的高海拔地区,较少扩散至低海拔的华中与华东,易受环境和全球气候变化的影响,生境人为干扰强烈,资源保护压力较大。据此,对弧隔鼠尾草亚属物种分布区进行了全面调查,结合标本记录,获得该类群具经纬度的物种分布记录2689条,海拔高度记录1007条,分布点涵盖286个县级地区。进一步对亚属内各组、系的水平与垂直分布格局深入分析。结果表明,亚属以横断山为核心区,主要分布于西藏东南至川西一带,零星扩散迁移至河北北部、湖北东部,其狭域分布的特有种比例非常高,占总物种数的45%。在物种海拔分布格局上,亚属内6个系具有替代分布现象,从高海拔的窄域分布物种逐渐过渡到低海拔的宽域分布物种。基于最大熵模型预测的亚属出现概率与物种实际分布范围基本吻合,从单一环境因子与出现概率的关系看,12月降水量、9月降水量、年温度变化范围、海拔、3月最高气温和温度季节性变化系数是影响物种分布的主导环境因子。鼠尾草雄蕊的分化是物种形成和多样性产生的关键因素,亚属内不同类群的分布格局与雄蕊花丝药隔比例的相关性表明,环境因子和传粉者选择可能共同作用形成现有弧隔鼠尾草亚属的分布格局。

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 different sections 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.