Evidence map›Paper›PMID 41414749›Full record

ArticleMolecular ecology resources2026

Unlocking Demography: Developing an eDNA-Based Toolkit to Measure Sex Ratios From Populations.

Emilie A Didaskalou, James France, Milena Cvijanović, Krijn B Trimbos, Tijana Vučić, Maja Ajduković, Ana Ivanović, Ben Wielstra, Peter M van Bodegom, Kathryn A Stewart

Abstract read
In one paragraph

Article in Molecular ecology resources, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. Article
  2. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

10 authors.

Emilie A DidaskalouInstitute of Environmental Sciences, Leiden University, Leiden, the Netherlands.ORCID https://orcid.org/0009-0005-8467-2780
James FranceInstitute of Biology, Leiden University, Leiden, the Netherlands.ORCID https://orcid.org/0000-0001-6651-3288
Milena CvijanovićInstitute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia.ORCID https://orcid.org/0000-0001-6258-3983
Krijn B TrimbosInstitute of Environmental Sciences, Leiden University, Leiden, the Netherlands.
Tijana VučićInstitute of Biology, Leiden University, Leiden, the Netherlands.ORCID https://orcid.org/0000-0002-8850-5251
Maja AjdukovićInstitute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia.ORCID https://orcid.org/0000-0001-9115-6622
Ana IvanovićFaculty of Biology, University of Belgrade, Belgrade, Serbia.
Ben WielstraInstitute of Biology, Leiden University, Leiden, the Netherlands.
Peter M van BodegomInstitute of Environmental Sciences, Leiden University, Leiden, the Netherlands.
Kathryn A StewartInstitute of Environmental Sciences, Leiden University, Leiden, the Netherlands.

Funding

Institute of Environmental Sciences, Leiden UniversityNederlandse Organisatie voor Wetenschappelijk Onderzoek VI.Vidi.213.088Serbian Ministry of Science, Technological Development and Innovation 451-03-136/2025-03/200007Serbian Ministry of Science, Technological Development and Innovation 451-03-136/2025-03/200178Serbian Ministry of Science, Technological Development and Innovation 451-03-137/2025-03/200178
6 · The paper itself

Abstract

Demographic information, such as sex ratios, is essential for understanding population dynamics and informing conservation strategies. Yet obtaining sex ratios in natural populations can be challenging due to logistical, ethical and legal constraints. Environmental DNA (eDNA) has revolutionised non-invasive biodiversity monitoring, but its potential for assessing demographic parameters remains largely unexplored. Here we present an eDNA-based method to monitor sex ratios of populations by quantifying sex-specific SNP alleles. Using RADseq data from Balkan crested newts (Triturus ivanbureschi), we identified a male-specific allele that was consistently present in all males and absent in females. We then developed a Droplet Digital PCR (ddPCR) assay to quantify allele ratios and validated it on mock (DNA extract mixtures) and eDNA samples with known sex ratios. Our sex-specific SNP assay successfully distinguished male- and female-biassed ratios in mock samples and showed a strong positive relationship between the proportion of males and the male-specific allele. While resolution was lower in eDNA samples, sex ratio estimates reflected population composition, particularly when corrected for biomass. Performance was mainly influenced by inter-individual variation in male allele copy numbers, but this effect diminished as the number of males increased, reflecting natural populations better. For effective field application, maximising nuclear eDNA recovery, validating marker specificity and accounting for species-specific life history traits when sampling will be crucial. With further field validation, our eDNA-based method could support large-scale, non-invasive sex ratio monitoring, offering valuable insights into species phenology and population dynamics to guide conservation efforts.

Indexed as

DNA, EnvironmentalGenetics, PopulationSex RatioAnimalsFemaleMalePolymerase Chain ReactionPolymorphism, Single NucleotideDNA, Environmentalamphibianbiodiversity monitoringdemographyenvironmental DNApopulation dynamics

Identifiers

PMID41414749
PMCPMC12715386

What Socratic holds

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LicenceCC BY
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Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.