Drivers of evolutionary changes and community dynamics in ancient Lake Ohrid across taxa: A synthesis of molecular, fossil and sediment record data

巴尔干的奥赫里德湖是欧洲最杰出的古湖泊，拥有非凡的物种丰富和几组生物的高度地方性。人们对产生这种生物多样性的过程知之甚少。对奥赫里德湖选定的底栖动物类群的初步遗传分析和分子钟估计表明，大多数特有类群在湖内进化而没有随着时间的推移发生重大变化，这表明在该湖的地质历史中没有发生灾难性事件。除其他外，这一假设启发了奥赫里德湖的ICDP运动（SCOPSCO）。从2013年4月初开始，SCOPSCO钻井作业成为有史以来最成功的ICDP湖钻井作业之一。截至2013年5月底，从奥赫里德湖采集了约2100米的沉积物样本。沉积物在4个不同的地点被回收，总回收率为约95%。首先分析表明，这些岩心提供了高质量的古湖泊数据的连续记录，并具有丰富的微观和宏观化石组合。此外，对岩心捕集器样品中硅藻组合的初步分析表明，硅藻群落随着时间的推移发生了显著变化。因此，本研究的主要目标是结合来自现存物种的分子钟信息以及微观和宏观化石数据，以及来自沉积物岩心的古环境数据（沉积学、地层学和古生境信息），推断古奥赫里德湖多个分类群的进化变化和群落更替的驱动因素。总体的工作假设是，奥赫里德湖缺乏灾难性事件，其高度的生态恢复能力可能减轻了环境干扰对湖泊分类群的不利进化影响。相反，这些变化可能主要引发了社区的流动。这为古湖泊研究提供了一条新的途径。在SCOPSCO钻井活动提供的协同作用的基础上，它结合了来自不同动物和原生生物群体的暂时明确的分子、古环境、古生物学和进化信息。此外，这些信息主要来自年龄控制的沉积物记录数据，这些数据跨越了古代湖泊的整个历史。

The Balkan Lake Ohrid is the most outstanding European ancient lake with an extraordinary species richness and a high degree of endemism in several groups of organisms. The processes generating this biodiversity are poorly understood. Preliminary genetic analyses of selected benthic animal groups in Lake Ohrid together with molecular clock estimations indicated that most of the endemic taxa evolved intralacustrine without major changes in diversification rates over time, pointing to an absence of catastrophic events during the geological history of the lake.This hypothesis has, among others, inspired the ICDP campaign (SCOPSCO) in Lake Ohrid. Starting in early April 2013, the SCOPSCO drilling operation became one of the most successful ICDP lake drilling campaigns ever conducted. Ca. 2100 m of sediment were sampled from Lake Ohrid until late May 2013. The sediments were recovered from four different sites with a total recovery of > 95%. First analyses indicated that the cores provide a continuous record of high-quality paleolimnological data and bear rich micro- and macrofossil assemblages. Moreover, preliminary analyses of diatom assemblages from core catcher samples showed significant shifts in diatom communities over time.Therefore, the main goal of the current proposal is to use a combination of molecular clock information derived from extant species as well as micro- and macrofossil data, on the one hand, and paleoenvironmental data from sediment cores (sedimentological, tephrostratigraphic, and paleo-habitat information), on the other, to infer the drivers of evolutionary changes and community turnovers in ancient Lake Ohrid across several taxa. The overall working hypothesis is that the absence of catastrophic events in Lake Ohrid and its high ecological resilience may have mitigated adverse evolutionary effects of environmental disturbances on lake taxa. Instead, these changes may have mainly triggered community turnovers.This proposal provides a novel approach in ancient lake studies. Building upon the synergies offered by the SCOPSCO drilling campaign, it combines temporarily explicit molecular, paleoenvironmental, paleontological, and evolutionary information from different animal and protist groups. Moreover, this information is primarily obtained from age-controlled sediment record data, which span the entire history of an ancient lake.