Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals

ABSTRACT Invertebrate‐derived DNA (iDNA) has been successfully utilized for surveying mammalian biodiversity in several ecosystems. Yet, as with all sampling methods, this approach suffers from potential biases, including those introduced by the choice of invertebrate sampler, as well as the stochas...

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Main Authors: Rosie Drinkwater, Elizabeth L. Clare, Stephen J. Rossiter
Format: Article
Language:English
Published: Wiley 2025-05-01
Series:Environmental DNA
Subjects:
Online Access:https://doi.org/10.1002/edn3.70121
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author Rosie Drinkwater
Elizabeth L. Clare
Stephen J. Rossiter
author_facet Rosie Drinkwater
Elizabeth L. Clare
Stephen J. Rossiter
author_sort Rosie Drinkwater
collection DOAJ
description ABSTRACT Invertebrate‐derived DNA (iDNA) has been successfully utilized for surveying mammalian biodiversity in several ecosystems. Yet, as with all sampling methods, this approach suffers from potential biases, including those introduced by the choice of invertebrate sampler, as well as the stochasticity of DNA amplification during PCR. Occupancy modeling is a statistical framework that can help account for imperfect detections in sampling and can be used to improve iDNA surveys. Using a case study based on the DNA screened from the blood meals of leeches, we demonstrate how multiscale occupancy models can be applied to the molecular detection of vertebrates to reveal the nuances in iDNA detections. Leeches were collected across a habitat degradation gradient in Sabah, Malaysian Borneo, in 2015 and 2016. We estimated three probabilities describing the occupancy, availability, and detection of three abundant mammals (bearded pig, muntjac and sambar deer) and compared how these values were impacted by environmental and technical covariates. For 2015, we found that null models without covariates revealed no clear differences in each of the three probabilities across taxa. However, in 2016, although the taxa have comparable occupancy, deviations occurred in the other two probabilities, with the sambar deer showing the lowest availability and muntjac with the lowest detection probability. Univariate models constructed for each taxon and year revealed differential impacts of the covariates; for example, a strong positive effect of DNA concentration on the detection of sambar deer and bearded pig was seen in 2016 only. Finally, our estimation of the minimum numbers of biological and technical replicates highlights the important trade‐off between achieving high probabilities of availability and detection and realistic amounts of sampling. Our results showcase the use of occupancy models for leech‐iDNA biodiversity surveys but highlight the potential effects of sample type, methodological design, and sample size.
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spelling doaj-art-904cff1941fc42e989c51b89c7e61a902025-08-20T03:27:44ZengWileyEnvironmental DNA2637-49432025-05-0173n/an/a10.1002/edn3.70121Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood MealsRosie Drinkwater0Elizabeth L. Clare1Stephen J. Rossiter2School of Biological and Behavioural Sciences Queen Mary University of London London UKDepartment of Biology York University Toronto Ontario CanadaSchool of Biological and Behavioural Sciences Queen Mary University of London London UKABSTRACT Invertebrate‐derived DNA (iDNA) has been successfully utilized for surveying mammalian biodiversity in several ecosystems. Yet, as with all sampling methods, this approach suffers from potential biases, including those introduced by the choice of invertebrate sampler, as well as the stochasticity of DNA amplification during PCR. Occupancy modeling is a statistical framework that can help account for imperfect detections in sampling and can be used to improve iDNA surveys. Using a case study based on the DNA screened from the blood meals of leeches, we demonstrate how multiscale occupancy models can be applied to the molecular detection of vertebrates to reveal the nuances in iDNA detections. Leeches were collected across a habitat degradation gradient in Sabah, Malaysian Borneo, in 2015 and 2016. We estimated three probabilities describing the occupancy, availability, and detection of three abundant mammals (bearded pig, muntjac and sambar deer) and compared how these values were impacted by environmental and technical covariates. For 2015, we found that null models without covariates revealed no clear differences in each of the three probabilities across taxa. However, in 2016, although the taxa have comparable occupancy, deviations occurred in the other two probabilities, with the sambar deer showing the lowest availability and muntjac with the lowest detection probability. Univariate models constructed for each taxon and year revealed differential impacts of the covariates; for example, a strong positive effect of DNA concentration on the detection of sambar deer and bearded pig was seen in 2016 only. Finally, our estimation of the minimum numbers of biological and technical replicates highlights the important trade‐off between achieving high probabilities of availability and detection and realistic amounts of sampling. Our results showcase the use of occupancy models for leech‐iDNA biodiversity surveys but highlight the potential effects of sample type, methodological design, and sample size.https://doi.org/10.1002/edn3.70121biodiversityBorneoinvertebrate‐derived DNAleech blood DNAmammalsoccupancy models
spellingShingle Rosie Drinkwater
Elizabeth L. Clare
Stephen J. Rossiter
Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
Environmental DNA
biodiversity
Borneo
invertebrate‐derived DNA
leech blood DNA
mammals
occupancy models
title Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
title_full Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
title_fullStr Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
title_full_unstemmed Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
title_short Improving the Understanding of Detections From iDNA Surveys in Malaysian Borneo With Multiscale Occupancy Models: A Case‐Study Using Leech Blood Meals
title_sort improving the understanding of detections from idna surveys in malaysian borneo with multiscale occupancy models a case study using leech blood meals
topic biodiversity
Borneo
invertebrate‐derived DNA
leech blood DNA
mammals
occupancy models
url https://doi.org/10.1002/edn3.70121
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