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

• Applicant: Privatdozentin Dr. Mona Hoppenrath
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 526201134

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.

• DFG Programme: Research Grants
• International Connection: Italy
• Cooperation Partner: Cecilia Teodora Satta
• Co-Investigator: Dr. Urban Tillmann