Expansion of the space by protists: recent speciation, phenotypic plasticity and adaptations to salinity

要想成功地保护生物多样性，必须清楚地认识现有的生物多样性，并了解新的生物多样性是如何产生的。最终产生生命多样性的一个关键过程被称为物种形成。今天，我们对这一现象的理解主要基于对众所周知的模型系统的研究。单细胞真核生物（原生生物）是地球上最多样化的生物群体之一，人们对其物种形成知之甚少。我们打算研究一群亲缘关系密切的原生生物，它们最初来自波罗的海，是沿海水域重要的初级生产者。像鞭毛藻这样的原中心体micans在不同的海洋和咸淡生境中茁壮成长。初步数据表明，各自的种群目前正在经历物种形成。对于一些世系来说，主要的驱动因素可能是盐度的变化。我们假设micans种群的多样性特征是由这一过程而不是表型可塑性来解释的。该项目的目的是确定这组密切相关的分类群的系统发育结构，评估当前的物种边界，并评估这些密切相关的原生生物在其进化背景下的转录组水平上的特定生理适应（特别是对盐度的适应）。该研究将首次详细研究许多密切相关的原生菌株的转录组，以了解微进化过程。我们将1)对来自不同生境的多种菌株的转录组进行测序和研究，2)描述和比较它们的形态特征，3)进行实验以表征对不同盐度的适应，4)分析它们在野外的生态位。我们期望对表达基因的研究将有助于确定这种辐射的驱动因素。特别是，我们打算弄清楚基因表达水平和氨基酸序列结构在相同盐度下不同但密切相关的物种之间以及同一物种在海洋和咸淡水中生活时不同种群之间的变化。为了研究不同菌株适应盐度变化的能力，我们将在实验室实验和波罗的海和地中海（沿盐度梯度）实地研究自然种群。总体目标是获得广泛分布的鞭毛藻micans复合体的综合数据集，最终提供对鞭毛藻多样化和物种形成的更好理解。

For successful biodiversity conservation it is important to clearly recognize current diversity and understand how new biodiversity generates. A key process that ultimately generates the diversity of life is known as speciation. Today our comprehension of this phenomenon is based mainly on the studies of well-known model systems. Little is known about speciation in unicellular eukaryotes (protists), one of the most diverse groups of organisms on Earth. We intend to study a flock of closely related protists initially described from the Baltic Sea, which are important primary producers in coastal waters. Prorocentrum micans like dinoflagellates thrive in different marine and brackish habitats. Preliminary data suggest that respective populations are currently undergoing speciation. For some lineages the main driver could be salinity variation. We hypothesize that diverse features of the P. micans like populations are explained by this process rather than by phenotypic plasticity. The aims of this project are to determine the phylogenetic structure of this group of closely related taxa, to evaluate current species boundaries and to assess specific physiological adaptations (in particular to salinity) on the transcriptome level of these closely related protists in the context of their evolution. The study will be the first detailed investigation of transcriptomes of many closely related protist strains in order to understand the process of microevolution. We will 1) sequence and study transcriptomes of multiple strains from different habitats, 2) describe and compare their morphological features, 3) perform experiments to characterize adaptations to different salinities and 4) analyse their ecological niches in the field. We expect that the investigation of the expressed genes will help to identify the drivers of this radiation. In particular, we intend to figure out how the level of gene expression and structure of amino acid sequences change between distinct but closely related species in the same salinity and between different populations of the same species when it inhabits marine and brackish waters. To study the ability of different strains to acclimate to salinity changes we will study natural populations in laboratory experiments and in the field of the Baltic and Mediterranean seas (along a salinity gradient). The overall goal is to obtain a comprehensive data set for the widespread dinoflagellate P. micans complex, that ultimately provide a better understanding of dinoflagellate diversification and speciation.