Estimation accuracy of species abundance based on environmental DNA with
relation to its production source and state suggested by meta-analyses
Abstract
Environmental DNA (eDNA) analysis is a promising tool for non-disruptive
and cost-efficient estimation of species abundance. However, its
practical applicability in natural environments is limited owing to a
potential gap between eDNA concentration and species abundance in the
field. Although the importance of accounting for eDNA dynamics, such as
transport and degradation, has been discussed, the influence of eDNA
characteristics, including production source and cellular/molecular
state, on the accuracy of eDNA-based abundance estimation was entirely
overlooked. We conducted meta-analyses using 44 of previous eDNA studies
and investigated the relationships between the accuracy
(R2) of eDNA-based abundance estimation and eDNA
characteristics. First, we found that estimated R2
values were significantly lower for crustaceans and mussels than fish.
This finding suggests that less frequent eDNA production of these taxa
owing to their external morphology and physiology may impede accurate
estimation of their abundance via eDNA. Moreover, linear mixed
modeling showed that, despite high variances, R2
values were positively correlated with filter pore size, indicating that
selective collection of larger-sized eDNA, which is typically fresher,
could improve the estimation accuracy of species abundance. Although our
collected dataset was somewhat biased to the studies targeting specific
taxa, our findings shed a new light on the importance of what
characteristics of eDNA should be targeted for more accurate estimation
of species abundance. Further empirical studies are required to validate
our findings and fully elucidate the relationship between eDNA
characteristics and eDNA-based abundance estimation.