Microbial sedimentary DNA from a cultural landscape disentangles the impacts of humans and nature over the past 13.5 thousand years

Abstract

Bacteria and archaea are currently under-characterised in palaeoecological studies, despite their ubiquity, high diversity and tight integration with the biotic and abiotic environment and human activity. The complexity of their assemblages, and the difficulties in separating living- from paleo-prokaryotes renders analyses challenging. Here we present an ancient prokaryote metagenomic time-series from a sediment core of Lake Constance, a large and deep perialpine lake from temperate Europe, spanning the last 13,500 years of natural and anthropogenic impact. We mapped DNA to reference genomes and estimated the DNA damage of taxa, which displayed a monotonic relationship with time. By constructing co-abundance networks we recognize major microbial assemblages, containing both ancient and living microbes, that show specific dynamics. Short-term and often low-abundance assemblages are linked to the Pleistocene-Holocene transition, floods and human activities. Noticeably, certain lineages harbouring microbes common in human-impacted environments expanded during the Middle Ages and Modern time. Some abundant taxa that were linked to various freshwater and soil environments persisted through millennia. By extricating various sources and trajectories of change, we demonstrate the power of prokaryotic sedimentary DNA in revealing long-term eco-evolutionary outcomes caused by both nature- and humans.