The project will focus on molecular metabarcoding approaches to obtain integrative species inventories for the ecosystems studied and to track population dynamics back in time by analysis of paleoenvironmental/ancient DNA. We will continue our investigations on invertebrates such as ostracods and extend this to other indicator species including diatoms and cyanobacteria. The parallel analysis of classical microfossil techniques (W6) and lipid biomarkers (W7) will allow to cross-evaluate paleo-environmental and climate reconstructions. The project will also work hand in hand with the doctoral research project studying the living microbial biosphere inhabiting deep sediments (W5). During fieldwork, the postdoctoral researcher will collect together with Chinese collaboration partners samples from deep sediment cores in the Nam Co catchment. These will be used for ancient DNA extraction in combination with DNA metabarcoding on Illumina platforms (e.g., Vences et al., 2016). Sediment sampling and paleoenvironmental DNA extraction will follow protocols specifically designed for extraction from ancient sediments to avoid contamination with modern material (e.g. Anderson-Carpenter et al., 2011, Rawlence et al., 2014).
Based on our expertise with metabarcoding and eDNA analyses, we are fully convinced that metabarcoding of extant organisms will be successful and generate a large set of highly relevant data, leading to a very efficient and objective high-throughput inventory of current and past freshwater diversity in the study system. We are aware that metabarcoding of ancient DNA is challenging and will require solving practical problems. We are optimistic to overcome these challenges and thereby provide pioneering studies in the molecular ecology of modern and ancient freshwater communities.
For terrestrial tissue, highest depletion rates of DNA seem to occur during decomposition in the terrestrial environment, and strongly decelerated DNA degradation is observed after embedding in lake sediments (Andersen-Carpenter et al., 2011). For tissue of aquatic organisms, factors influencing the preservation or loss of DNA are largely unknown. Our Chinese colleagues will help to collect lake water, water filtrate, surface sediment, sediment cores, catchment soils and relevant samples at selected lake(s) (Nam Co and neighboring lakes) on TP. Microbial community structure and activity will be compared against amount and diversity of (paleo-) environmental DNA extracted from sediments (P1), to access potential connections between DNA preservation and microbial activity. This shall contribute to develop more precise site selection criteria for paleoenvironmental DNA studies and enhance the predictability of success when applying the paleoenvironmental DNA approach. DNA analyses will be performed in laboritories of our Chinese colleagues in Beijing, which will also help the candidate getting access to partnering labs.
Prof. Dr. Michael Pester, Leibniz Institute DSMZ & TU Braunschweig
Prof. Dr. Antje Schwalb, TU Braunschweig
Prof. Dr. Fahu Chen, ITP