Effects of Quaternary climate changes on morphological variability of aquatic invertebrates (ostracodes) within the ICDP project NamCore

青藏高原是山地生物多样性的热点地区，山地环境演变与季风波动和轨道强迫气候变化之间存在着相互作用。许多现代谱系的多样化发生在2 Ma和150 ka之间，被认为是气候波动和相关环境变化的结果。然而，青藏高原上大多数生态系统，尤其是湖泊的确切起源和发展在很大程度上是未知的。因此，到目前为止，季风变化、局部或区域环境反应与物种分布或多样性之间的关系尚未得到认识。纳木错钻探项目的主要目的是在西藏纳木错湖（Co = lake）沉积物上建立一个详细的季风历史的大陆记录，时间尺度为0.5-1 Ma。这种长时间的连续记录使得研究第四纪生物动态（物种多样性和分布、进化）与气候变化的关系成为可能。了解水生生物的形态变异可以做出有价值的贡献，因为它取决于环境和遗传的影响。介形类（节肢动物、甲壳类）是回答这些问题的理想生物指标，因为它们是唯一一种在湖泊环境中形成骨骼碳酸盐的水生无脊椎动物，它们容易和丰富地保存下来，并且由于它们对生态变化的（物种特异性）敏感性，可以提供大量的古环境信息。我们建议对纳木错湖介形类分布的长期演变及其形态变异进行研究，以揭示该湖是作为冰川避难所而持续存在着介形类，还是在冰期气候变冷时介形类灭绝，并随着温度的升高而不断地在湖中定居。刻画现代种群的形态-环境关系将有助于了解化石介形类的形态变异是否反映了环境变化（如温度）或种内和/或种间分化。本文将根据白羊草瓣大小、形状和纹饰的形态计量学数据进行分析。生态表型特征的确定将揭示环境变化对介形虫瓣形态的影响，特别是哪些形态特征是特定生态参数的敏感指标。因此，这种新方法将为介形类对气候变化的响应及其对介形类进化和（古）生态的影响提供新的见解，特别是对青藏高原。

The interplay between the evolution of the mountainous environments, monsoonal fluctuations and orbitally-forced climate changes resulted in the Tibetan Plateau (TP) being a montane biodiversity hotspot. Diversification of many modern lineages occurred between 2 Ma and 150 ka assumed to result from climate fluctuations and associated environmental changes. The exact origin and development of most ecosystems, especially lakes, on the TP is however largely unknown. Hence, relationships between monsoonal changes, local or regional environmental responses, and species distribution or diversity are not recognized so far. The main aim of the Nam Co Drilling project is to establish a continental record of detailed monsoon history on orbital to suborbital timescales back to 0.5-1 Ma on sediments of the Tibetan lake Nam Co (Co = lake). This long continuous record enables to investigate Quaternary biotic dynamics (species diversity and distribution, evolution) in relation to climate changes. Understanding the morphological variability of aquatic organisms can make a valuable contribution, as it depends on environmental and genetic influences. Ostracodes (Arthropoda, Crustacea) are ideal bioindicators to answer these questions since they are the only aquatic invertebrates in lacustrine settings forming skeletal carbonates which are easily and abundantly preserved, and can provide plenty of paleoenvironmental information due to their (species-specific) sensitivity for ecological changes. We suggest to investigate the long-term evolution of ostracode distribution and their morphological variability in Nam Co. This will reveal if the lake served as glacial refugium and was continuously populated by ostracodes, or if ostracodes became extinct when climate was cooling during glacials and repeatedly colonized the lake with, e.g., increasing temperatures. Characterization of morphology-environment relationships of modern populations will help to understand if morphological variability of the fossil ostracodes reflect environmental changes (e.g., temperature) or intra- and/or interspecific differentiation. Analyzes will be based on morphometric data of valve size, shape and ornamentation of L. sinensis-L. dorsotuberosa, the most dominant ostracode species in Nam Co. Identification of ecophenotypical characteristics will disclose how environmental changes impact ostracode valve morphology, and in particular which morphological traits are sensitive indicators for specific ecological parameters. This novel approach will therefore provide new insights on responses of the ostracodes to climate change and their effects on ostracode evolution and (paleo)ecology in general and in particular for the TP.