Accumulation curves of environmental DNA sequences predict coastal fish
diversity in the Coral Triangle
Abstract
Environmental DNA (eDNA) has the potential to provide more comprehensive
biodiversity assessments particularly for vertebrates in species-rich
regions. Yet, this method requires the completeness of a reference
database, i.e. a list of DNA sequences attached to each species, which
is never met. As an alternative, a diversity of Operational Taxonomic
Units (OTUs) can be extracted from eDNA metabarcoding. However, the
extent to which the diversity of OTUs provided by a limited eDNA
sampling effort can predict regional species diversity is unknown. Here,
by modelling OTU accumulation curves of eDNA seawater samples across the
Coral Triangle, we obtained an asymptote reaching 1,531 fish OTUs while
1,611 fish species are recorded in the region. Besides, we also
accurately predict (R² = 0.92) the distribution of species richness
among fish families from OTU-based asymptotes. Thus, the multi-model
framework of OTU accumulation curves extends the use of eDNA
metabarcoding in ecology, biogeography and conservation.