The importance of the uplift of the Qinghai-Tibetan Plateau for the diversity of alpine plants

生物多样性在地球上分布不均。有几个因素可以导致一个地区的物种多样性很高，例如，该地区的年龄(物种随着时间的积累)，扩散不对称(由于一个地区的条件比另一个地区更有利，移民比迁出更多)，更高的多样化比率(由于内在或外部原因)，或两者的组合。在环境发生重大变化(例如地形变化)后开辟新的生态位，可能是高海拔生境物种多样化的重要驱动因素。该项目旨在以物种丰富的虎耳草属(Saxifraga)为模式，根据全球气候变化和古新世至更新世的地质历史，揭示高山植物演化的时空框架。首先，我们将研究青藏高原的隆升及其相关的气候变化对高山物种多样性的影响。为了了解青藏高原与世界其他山地系统之间的区系交流，我们还将研究该属的传播史。最后，我们将确定重要的生态因素，以实现虎耳草的多样化。通过将多基因系统发育与生物地理分析相结合，我们想要回答以下问题：(1)虎耳草科树冠群的年龄是多少？虎耳草的多样性是否与青藏高原的隆升有关？(2)移民和原地多样性对青藏高原及邻近地区虎耳草物种多样性的相对贡献是什么？此外，结合物种地理和生态属性的信息(分布范围；生态/气候空间)和分布区地质历史的知识，我们想回答以下问题：(3)同域姐妹类群是否比异地姐妹类群具有更强的生态位分离？生态位保守主义还是生态位分化在虎耳草中占主导地位？(4)虎耳草中的杂交物种在生态和遗传上是否存在差异？这些物种分化的生态因素是什么？该项目的结果还将作为制定国际自然保护联盟濒危物种红色名录评估的信息来源。此外，虎耳草的DNA数据可能作为条形码，用于识别存在于虎耳草中的神秘物种和其他未被研究的物种复合体的分类群。莱比锡大学的Lipsiense植物标本馆及其合作机构将在该项目过程中从亚洲制造的新植物收藏中受益匪浅。

Biodiversity is unevenly distributed on Earth. There are several factors which can lead to high species diversity in an area, like e.g. age of the area (accumulation of species over time), dispersal asymmetries (more immigration than emigration due to more favourable conditions in one area compared to another area), higher diversification rates (due to intrinsic or extrinsic reasons), or a combination thereof. The opening of new ecological niches following major changes in the environment (e.g. orographic changes) may constitute an important driver for the diversification of species of higher elevation habitats. The project proposed here aims at unveiling the spatio-temporal framework of the evolution of alpine plants, using the species-rich genus Saxifraga (Saxifragaceae) as a model, in the light of global climate change and geological history from Palaeocene to Pleistocene. First, we will investigate the effect of the uplift of the Qinghai-Tibetan Plateau (QTP) and its associated climatic changes on the diversification of alpine species. To understand the floristic exchanges between the QTP and other mountain systems of the world, we will also study the dispersal history of this genus. Finally, we will identify important ecological factors for the diversification of Saxifraga. By combining multi-gene phylogenies with biogeographic analyses, set in a temporal context by fossil constraints for Saxifragaceae and relatives, we want to answer the following questions: (1) How old is the crown group of Saxifraga? Was diversification in Saxifraga associated with the uplift of the Qinghai-Tibetan Plateau? (2) What is the relative contribution of immigration versus in situ diversification to the high species diversity of Saxifraga in the Qinghai-Tibetan Plateau and neighbouring regions? Furthermore, together with information on the geographical and ecological attributes of species (distribution range; ecological/climate space) and knowledge about the geological history of the distributional areas, we want to answer the following questions: (3) Do sympatric sister taxa have a stronger niche separation than allopatric sister taxa? Is niche conservatism or niche divergence dominant in Saxifraga? (4) Are hybridising species in Saxifraga ecologically and genetically differentiated? What are the ecological factors involved in the divergence of these species? The results of this project will also serve as source of information for setting up IUCN Red List assessments for species under threat. In addition, DNA data of Saxifraga might potentially act as barcodes for the identification of cryptic species and other taxa of under-studied species complexes that exist in Saxifraga. Herbarium Lipsiense at Leipzig University and its partner institutions will greatly benefit from the new plant collections made in Asia during the course of this project.