| Popis: |
Global biodiversity is declining at an alarming pace due to anthropogenic factors. It is imperative to monitor the health of ecosystems through biodiversity assessments. But existing biodiversity assessment approaches are not scalable to assess the complete diversity of all the life forms in large ecosystems. We hypothesized that the extracellular environmental DNA (eDNA) released by natural cell lysis of biological matter in aquatic ecosystems is a repertoire of genetic material from all the inhabiting organisms and deep sequencing of extracellular eDNA could enable the detection of taxa across the tree of life. We developed a lysis-free and PCR-free workflow to directly enrich and sequence extracellular eDNA from environmental water samples and demonstrate its utility for taxonomic diversity assessment across the tree of life in a large biodiverse model aquatic ecosystem (Ramsar wetland: Chilika lagoon). Using incidence-based asymptotic richness analysis, we estimated that Chilika harbors about 1071 families across the tree of life comprising approximately 799 families of Eukaryotes, 230 families of Bacteria, 27 families of Archaea, and 13 families of DNA Viruses. We also quantified the compositional changes in the relative abundance of families across the tree of life and detected a higher temporal variation (46%) across the seasons than the spatial variation (37%) across the lagoon. With the increasing genomic resources and decreasing sequencing costs, we envision the wide adoption of extracellular eDNA- based taxonomic diversity assessment across the tree of life to track the future biodiversity loss and aid the conservation, restoration, and management efforts in the Anthropocene. |
