A review on the applications and recent advances in environmental DNA (eDNA) metagenomics

Progressions accomplished in the field of molecular biology amid the most recent decade has changed the way in which we contemplate biodiversity on earth. Together with the accessibility of new molecular techniques like high-throughput sequencing (HTS), a prompt metamorphosis was attained in understanding the behaviour and biodiversity patterns of biological systems at a level never before possible. The DNA gathered from different environmental samples (named as environmental DNA or eDNA) when coupled with HTS offers a powerful tool by empowering the census of individual species on a global scale in real time. The applications of eDNA are transpiring in different domains, for example, trophic and community ecology (functional diversity, ecosystem dynamics and prey-predator interactions), biomonitoring, conservation biology (single and multi species detection, abundance estimates), invasion biology (early species detection, passive surveillance) and environmental assessment (detection of anthropogenic contamination, microbial source tracking). However, more empirical data is required to standardize the specific sampling procedures to achieve in the best possible way. Although the application of eDNA is intensifying swiftly at a global scale, there are still some knowledge gaps, especially with methods and applications. These procedures require some refinements and validations to diminish the burden of false positives/negatives. Considering these impediments, we mainly concentrated in pooling together the most recent outcome of research articles (2008-2019) available in eDNA analysis that converse about diverse ecosystems (freshwater, marine and terrestrial habitats). We likewise discussed developments and limitations that are generally concerned with eDNA exercise in the present review.