J Syst Evol

• Research Articles •    

The evolutionary rate of leaf osmotic strength drives diversification of Primulina species in karst regions

Gui‐Lin Wu1, Qing Ye2,3,4*, Hui Liu4, De‐Xiang Chen1, Zhang Zhou1, Ming Kang4, Hang‐Hui Kong4, Zhi‐Jing Qiu5, and Hui Wang5   

  1. 1 Hainan Jianfengling Forest Ecosystem National Field Science Observation and Research Station, Research Institute of Tropical Forestry, Chinese Academy of Forestry, Guangzhou 510520, China
    2 College of Life Sciences, Gannan Normal University, Ganzhou 341000, Jiangxi, China
    3 Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
    4 Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
    5 Key Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Sciences, Shenzhen 518004, China
  • Received:2021-09-06 Accepted:2022-08-26 Online:2022-09-14


Leaf water storage capacity and osmotic strength are important traits enabling species to adapt to environments that are often moisture limited. However, whether these drought tolerance traits are correlated with the species diversification rate (DR) of plant lineages is yet to be determined. In this study, we selected a species-rich genus (Primulina) of plants widely distributed in karst regions in which species frequently experience variable periods of drought. We measured water storage capacity-related traits (including leaf thickness and water content per mass) and saturated osmotic strength in the leaves of 58 Primulina species growing in a common garden. Subsequently, using phylogenetic methods, we examined the relationships between the rate of species diversification and the drought tolerance traits and between the species DR and evolutionary rates of these traits. We found that neither water storage capacity nor saturated osmotic strength showed significant relationships with the rate of species diversification. However, the evolutionary rate of saturated osmotic strength showed a significant correlation with the species DR, although no comparable significant relationship was detected regarding the evolutionary rate of water storage capacity. Our study indicates that the diversification among Primulina species has typically been accompanied by an extensive divergence of leaf osmotic strength but not a divergence in leaf water storage capacity. These findings will enhance our current understanding of how drought tolerance influences the diversification of plant species in karst regions.

Key words: diversification rate, karst, leaf drought tolerance, osmotic strength, phylogenetic analysis, water storage capacity