Biology subjects

Haderle, R.

Publications and source records attributed to Haderle, R..

3 recordsLinked to original sources

bioRxiv2026

TRIDENT (Taxonomic Resolution and IDentification using Environmental dNa Traces): An Optimized Algorithm for Vertebrate Taxonomic Assignments in eDNA Metabarcoding, Integrating Molecular, Taxonomic, and Ecological Criteria

Environmental DNA (eDNA) metabarcoding has become a powerful approach for large-scale biodiversity assessment, yet taxonomic assignment remains one of its most critical error-prone steps. Current bioinformatic pipelines rely on molecular similarity searches against reference databases, but assignment accuracy is constrained not only by short marker length and database incompleteness, but also by fundamental limitations, including recent species radiations, incomplete lineage sorting, introgression, NUMTs, and the imperfect correspondence between genetic variation and species boundaries. Here, we present TRIDENT (Taxonomic Resolution and IDentification using Environmental dNa Traces), an automated and simple protocol designed to improve taxonomic assignments in eDNA metabarcoding. Initially developed for marine vertebrates, TRIDENT may be used with any barcode and integrates three complementary sources of evidence: molecular similarity (NCBI/GenBank and BOLD), curated taxonomic information (WoRMS), and ecological plausibility derived from biogeographic occurrence data (GBIF). The workflow sequentially constructs candidate taxon lists based on sequence similarity, expands them through taxonomic hierarchies, and filters them using spatial occurrence constraints. It further identifies possible taxa lacking reference barcodes and evaluates their plausibility through CO1-based similarity if data exist in BOLD. TRIDENT has been implemented as a source-available Python tool and tested using empirical eDNA datasets from marine vertebrates as well as simulated communities. Results demonstrate that the tool produces taxonomic assignments consistent with expert manual curation while substantially reducing processing time and attention errors caused by manual processing of large datasets. By combining molecular, taxonomic, and ecological criteria within a single framework, TRIDENT improves transparency and reproducibility and provides a robust and flexible solution strengthening confidence in taxonomic identifications in eDNA-based biodiversity assessments.

Molecular Biology↗

bioRxiv2026

The old pipe gives the sweetest smoke: A phylogenetic turn for eDNA metabarcoding

Environmental DNA (eDNA) metabarcoding has transformed biodiversity monitoring, yet most analyses rely on taxonomic metrics that are sensitive to methodological variation and limit cross-study comparability. We propose a "phylogenetic turn" in eDNA analysis through the integration of phylogenetic diversity (PD) metrics. By incorporating evolutionary relationships, PD reduces dependence on species-level resolution, increases robustness to detection biases, and better captures the evolutionary "option value" of biodiversity. We synthesize key PD metrics across richness, divergence, and regularity, emphasizing the use of standardized effect sizes (SES) for ecological interpretation while addressing challenges in metric selection. We apply this framework to five marine eDNA datasets (2021-2025) spanning ecologically and geographically contrasting ecosystems, from tropical to Arctic regions, and encompassing a wide gradient of anthropogenic pressure. Across datasets, we identify consistent patterns: anthropized ecosystems exhibit high taxonomic richness but reduced phylogenetic diversity, indicating phylogenetic clustering, whereas less disturbed systems show lower richness but greater evolutionary breadth. These findings demonstrate that PD reveals ecological structure not captured by taxonomic metrics, including signatures of environmental filtering and community assembly processes. By providing a reproducible analytical workflow based on standardized eDNA datasets, we position phylogenetic diversity as a critical bridge between eDNA data and conservation frameworks. Ultimately, eDNA-based phylogenetic approaches open new avenues for decoding global biodiversity patterns across heterogeneous ecosystems.

genetics↗

bioRxiv2025

A Multi-Taxa Approach to Estuarine Biomonitoring: Assessing Vertebrate Biodiversity and Ecological Continuity using Environmental DNA Metabarcoding in the Rance River (Brittany, France)

Estuaries are ecologically vital yet highly impacted ecosystems that serve as transitional zones between land and sea. Monitoring their biodiversity is essential but challenging due to their dynamic nature and the transient presence of many species. Traditionally actinopterygian monitoring in these systems still relies on conventional and intrusive methods such as gill nets and trawls. Environmental DNA (eDNA) metabarcoding offers a non-invasive, multi-taxa alternative that can complement these traditional approaches. Here, we applied an eDNA-based metabarcoding approach to characterize vertebrate diversity in the Rance Estuary, located in the Brittany Region of France. Water samples were collected from five stations spanning marine to freshwater environments. Special attention was given to two stations located upstream and downstream of the tidal power plant (TPP) dam to assess its potential impact on ecological continuity. We detected a total of 124 distinct vertebrate MOTUs--comprising actinopterygians, birds, mammals, and amphibians. Taxonomic composition followed the estuarine gradient, with Jaccard dissimilarity increasing with distance from the sea and largely driven by species turnover. While taxonomic and phylogenetic diversity remained relatively stable across the vertebrate community, functional diversity revealed an increasing terrestrial influence. For actinopterygians, taxonomic diversity decreased upstream, whereas phylogenetic and functional diversity indicated fine-scale structuring, even among nearby stations. This approach enabled the development of biodiversity metrics and facilitated comparisons with previous actinopterygian monitoring surveys in the same area based on conventional methods (scientific fishing using nets and dredges). Our results emphasise the potential of eDNA for holistic estuarine biomonitoring and establish a valuable baseline for future non-invasive assessments.

ecology↗