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匀。有几个因素可能导致一个地区的物种多样性高，例如该地区的年龄（物种随着时间的推移而积累），扩散不对称（由于一个地区比另一个地区更有利的条件，移民比移民更多），更高的多样化率（由于内在或外在原因），或其组合。在环境发生重大变化（如地形变化）后出现新的生态位，可能是高海拔生境物种多样化的重要驱动力。本研究以物种丰富的虎耳草属（虎耳草科）为模式，结合古新世至更新世的全球气候变化和地质历史，揭示高山植物演化的时空框架。首先，我们将调查青藏高原（QTP）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系之间的植物区系交流，我们还将研究该属的扩散历史。最后，我们将确定重要的生态因子的多样化虎耳草。 通过结合多基因的亲缘关系和植物地理学分析，在虎耳草科及其近缘植物的化石限制的时间背景下，我们想回答以下问题：（1）虎耳草属植物的冠群有多老？虎耳草属植物的多样性与青藏高原的隆升有关吗？(2)在青藏高原及其邻近地区，移民与原地多样化对虎耳草高物种多样性的相对贡献是什么？此外，结合物种的地理和生态属性（分布范围、生态/气候空间）以及分布区的地质历史知识，我们希望回答以下问题：（3）同域姊妹类群是否比异域姊妹类群具有更强的生态位分离？虎耳草属植物中是生态位保守还是生态位趋异占主导地位？(4)虎耳草属的杂交种在生态和遗传上有差异吗？这些物种分化的生态因素是什么？ 该项目的结果还将作为建立世界自然保护联盟濒危物种红色名录评估的信息来源。此外，虎耳草属的DNA数据可能潜在地作为条形码，用于鉴定存在于虎耳草属中的隐蔽物种和其他未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期间从亚洲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.