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

山地环境演变、季风波动和轨道强迫气候变化之间的相互作用导致青藏高原成为山地生物多样性的热点。许多现代谱系的多样化发生在2 Ma至150 ka之间，被认为是气候波动和相关环境变化的结果。然而，茶多酚上大多数生态系统，特别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、当地或区域环境响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建立一个详细的大陆季风史记录，记录西藏纳木错(Co=Lake)沉积物从轨道到亚轨道的时间尺度，追溯到0.5-1 Ma。这一漫长的连续记录使研究与气候变化有关的第四纪生物动力学(物种多样性和分布、进化)成为可能。了解水生生物的形态变异性可以做出有价值的贡献，因为它取决于环境和遗传影响。介形类(节肢动物，甲壳纲)是回答这些问题的理想生物指标，因为它们是唯一在湖泊环境中形成骨骼碳酸盐的水生无脊椎动物，容易和丰富地保存下来，并且由于它们(物种特有的)对生态变化的敏感性，可以提供大量的古环境信息。我们建议研究纳木错介形虫分布及其形态变异的长期演变。这将揭示该湖泊是否作为冰川避难所并持续繁殖介形虫，或者介形虫是否在冰期气候变冷时灭绝，并随着气温的升高而反复定居。现代种群形态-环境关系的特征将有助于理解介形类化石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。分析将基于形态计量学数据的瓣片大小，形状和纹饰的中华绒毛。生态表型特征的鉴定将揭示环境变化如何影响介形虫瓣膜的形态，特别是哪些形态特征是特定生态参数的敏感指示器。因此，这一新的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TP。

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.