中国南方苦苣苔科植物在喀斯特地貌和丹霞地貌上的适应分化

Adaptive Differentiation of Gesneriaceae on Karst and Danxia Landforms in Southern China

关键词:  适应分化  生境异质性  物种形成  特有种

Key words:  adaptive differentiation  habitat heterogeneity  speciation  endemic species

摘要:

中国南方同域分布着大面积的喀斯特地貌和丹霞地貌，其形成的异质性生境可能促进物种的分化适应以实现植物物种形成与维持。本文比较研究了中国南方喀斯特地貌和丹霞地貌的土壤与生境差异，分析了苦苣苔科植物在这两类生境上的分布格局、专性程度等，解释这两类生境对苦苣苔科物种分化与特有种维持的可能作用。结果显示：丹霞地貌的土壤更偏酸性，土壤含钾量极高；喀斯特地貌土壤则呈明显碱性，土壤含钙量极高。苦苣苔科植物专性或偏好喀斯特生境的物种有162种（占31.58%），花期集中在4—10月（87.04%）；丹霞生境专性或偏好的物种27种，花期集中在8—9月（44.44%）。另外有一部分类群同时在喀斯特地貌和丹霞地貌有着较广的分布，但也存在一定的分化；如在两类生境都有大量分布的闽赣长蒴苣苔，在丹霞地貌上的种群花期较喀斯特种群的约早2个月。这些结果证实，中国南方喀斯特和丹霞地貌不同的土壤性质及相关环境与气候特点，促进了苦苣苔科植物物种分化，可能是我国南方苦苣苔科植物具有较多狭域特有种的一个重要原因。

Abstract:

Large areas of karst landforms and Danxia landforms are distributed in the same area of southern China,and the heterogeneous habitats formed may promote the differentiation and adaptation of species to achieve plant species formation and maintenance. This paper compares and studies the soil and habitat differences between the karst landforms and the Danxia landforms in southern China,and analyzes the distribution patterns and degree of specialization of the Gesneriaceae plants in these two habitats to explain the possible effects of these two habitats on species differentiation and endemic species maintenance of the Gesneriaceae genus. The results show that the soil of Danxia landform is more acidic,the potassium content of soil is extremely high,while the soil of karst landform is obviously alkaline,and the soil contains very high calcium. There are 162 species (31.58%) of Gesneriaceae plants specific or preferred to karst habitats,and the flowering period is concentrated in April-October (87.04%). There are 27 species specific or preferred to Danxia habitats,and the flowering period is concentrated at August-September (44.44%). In addition,some taxa have a wide distribution in karst landforms and Danxia landforms,but there are also certain differentiations. For example,there are a large number of Hemiboea henryi distributed in both types of habitats,and the flowering period of the population on Danxia landforms is about 2 months earlier than that of the population on karst landforms. These results confirmed that different soil properties and related environmental and climatic characteristics of the karst landforms and Danxia landforms in southern China promoted the species differentiation of Chinese Gesneriaceae,which may be an important reason for more endemic species in the narrow domain of southern China.