Ancient DNA Metagenome

Ancient lake sediments store biological, chemical and physical information that allows reconstructing environmental and climate changes in time and space. Aquatic and terrestrial plant and animal remains in particular have been used to assess past ecosystem changes and to provide estimates of precipitation and temperature variability. Scientists however, are well aware of the fact that the analysed microscopic and macroscopic fossil assemblages only represent a tiny fraction of all the organisms that had existed at a certain time in the past and that each of the analytical methods employed has its specific limitation. Recent advances in environmental DNA analyses from ancient sediments that make use of new large-scale sequencing technologies now offer the unprecedented opportunity to unravel a complementary spectrum of ancient faunal, floral and microbial remains than those identified by traditional micro- and macrofossil analyses and moreover permit identification at lower taxonomic levels (e.g., Parducci et al. 2012, 2013, 2014; Willerslev et al. 2014; Wilmshurst et al. 2013). As such, ancient DNA (aDNA) studies have the potential to revolutionise our understanding of the response of past ecosystems to climatic changes.Environmental aDNA extracted from lake sediments derives from plant (rootlets, leaves, microbes) and animal tissues, including urine (Willerslev et al. 2014). Although aDNA is present in low quantities in sediments and is fragmented, such DNA molecules are of sufficiently good quality for the retrieval and taxonomic identification of animals, plants and microbes using massively parallel sequencing methodologies (e.g., Andersen et al. 2011).