Developing forensic tools for an African timber

Regional origin is revealed by genetic characteristics, but not by isotopic signature

Mart Vlam*, Arjen de Groot, Arnoud Boom, Paul Copini, Ivo Laros, Katrui Veldhuijzen, David Zakamdi, Pieter A. Zuidema

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Scopus)

Abstract

Combatting illegal timber trade requires forensic tools that independently verify claimed geographic origin of timber. Chemical and genetic wood characteristics are potentially suitable tools, but their performance at small spatial scales is unknown. Here we test whether stable isotopes and microsatellites can differentiate Tali timber (Erythrophleum spp.) at the level of forest concessions. We collected 394 wood samples from 134 individuals in five concessions in Cameroon and Congo Republic. The nearest neighbour concessions were 14 km apart and the furthest pair 836 km apart. We constructed genetic profiles using eight nuclear microsatellite markers and measured concentrations of δ18O, δ15N and δ13C. We differentiated provenances using PCA (microsatellites), ANOVA and kernel discriminant analysis (isotopes). Next, we performed assignment tests using blind samples (n = 12, microsatellites) and leave one out cross validation (LOOCV, isotopes). Isotopic composition varied strongly within concessions and only δ13C differed significantly between two concessions. As a result, LOOCV performed only marginally better than random. Genetic differentiation among provenances was also relatively low, but private alleles were commonly found. Bayesian clustering analysis correctly assigned 92% of the blind samples, including those of nearby concessions. Thus, Tali timber can be successfully assigned to the concession of origin using genetic markers, but not using isotopic composition. Isotopic differentiation may be possible at larger spatial scales or with stronger climatic or topographic variation. Our study shows that genetic analyses can differentiate the geographic origin of tropical timber at the scale of forest concessions, demonstrating their potential as forensic tools to enforce timber trade legislation.
Original languageEnglish
Pages (from-to)262-271
JournalBiological Conservation
Volume220
DOIs
Publication statusPublished - 1 Apr 2018

Fingerprint

provenance
timber
microsatellite repeats
isotopes
Erythrophleum
timber trade
tropical wood
talus
Republic of the Congo
Cameroon
sampling
discriminant analysis
laws and regulations
stable isotopes
isotopic composition
analysis of variance
testing
isotope
alleles
genetic variation

Keywords

  • DNA
  • Geographic origin
  • Microsatellites
  • Stable isotopes
  • Timber forensics
  • Tropical timber

Cite this

@article{ad64bc33402a43cfb86e405c9bf66060,
title = "Developing forensic tools for an African timber: Regional origin is revealed by genetic characteristics, but not by isotopic signature",
abstract = "Combatting illegal timber trade requires forensic tools that independently verify claimed geographic origin of timber. Chemical and genetic wood characteristics are potentially suitable tools, but their performance at small spatial scales is unknown. Here we test whether stable isotopes and microsatellites can differentiate Tali timber (Erythrophleum spp.) at the level of forest concessions. We collected 394 wood samples from 134 individuals in five concessions in Cameroon and Congo Republic. The nearest neighbour concessions were 14 km apart and the furthest pair 836 km apart. We constructed genetic profiles using eight nuclear microsatellite markers and measured concentrations of δ18O, δ15N and δ13C. We differentiated provenances using PCA (microsatellites), ANOVA and kernel discriminant analysis (isotopes). Next, we performed assignment tests using blind samples (n = 12, microsatellites) and leave one out cross validation (LOOCV, isotopes). Isotopic composition varied strongly within concessions and only δ13C differed significantly between two concessions. As a result, LOOCV performed only marginally better than random. Genetic differentiation among provenances was also relatively low, but private alleles were commonly found. Bayesian clustering analysis correctly assigned 92{\%} of the blind samples, including those of nearby concessions. Thus, Tali timber can be successfully assigned to the concession of origin using genetic markers, but not using isotopic composition. Isotopic differentiation may be possible at larger spatial scales or with stronger climatic or topographic variation. Our study shows that genetic analyses can differentiate the geographic origin of tropical timber at the scale of forest concessions, demonstrating their potential as forensic tools to enforce timber trade legislation.",
keywords = "DNA, Geographic origin, Microsatellites, Stable isotopes, Timber forensics, Tropical timber",
author = "Mart Vlam and {de Groot}, Arjen and Arnoud Boom and Paul Copini and Ivo Laros and Katrui Veldhuijzen and David Zakamdi and Zuidema, {Pieter A.}",
year = "2018",
month = "4",
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doi = "10.1016/j.biocon.2018.01.031",
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Developing forensic tools for an African timber : Regional origin is revealed by genetic characteristics, but not by isotopic signature. / Vlam, Mart; de Groot, Arjen; Boom, Arnoud; Copini, Paul; Laros, Ivo; Veldhuijzen, Katrui; Zakamdi, David; Zuidema, Pieter A.

In: Biological Conservation, Vol. 220, 01.04.2018, p. 262-271.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Developing forensic tools for an African timber

T2 - Regional origin is revealed by genetic characteristics, but not by isotopic signature

AU - Vlam, Mart

AU - de Groot, Arjen

AU - Boom, Arnoud

AU - Copini, Paul

AU - Laros, Ivo

AU - Veldhuijzen, Katrui

AU - Zakamdi, David

AU - Zuidema, Pieter A.

PY - 2018/4/1

Y1 - 2018/4/1

N2 - Combatting illegal timber trade requires forensic tools that independently verify claimed geographic origin of timber. Chemical and genetic wood characteristics are potentially suitable tools, but their performance at small spatial scales is unknown. Here we test whether stable isotopes and microsatellites can differentiate Tali timber (Erythrophleum spp.) at the level of forest concessions. We collected 394 wood samples from 134 individuals in five concessions in Cameroon and Congo Republic. The nearest neighbour concessions were 14 km apart and the furthest pair 836 km apart. We constructed genetic profiles using eight nuclear microsatellite markers and measured concentrations of δ18O, δ15N and δ13C. We differentiated provenances using PCA (microsatellites), ANOVA and kernel discriminant analysis (isotopes). Next, we performed assignment tests using blind samples (n = 12, microsatellites) and leave one out cross validation (LOOCV, isotopes). Isotopic composition varied strongly within concessions and only δ13C differed significantly between two concessions. As a result, LOOCV performed only marginally better than random. Genetic differentiation among provenances was also relatively low, but private alleles were commonly found. Bayesian clustering analysis correctly assigned 92% of the blind samples, including those of nearby concessions. Thus, Tali timber can be successfully assigned to the concession of origin using genetic markers, but not using isotopic composition. Isotopic differentiation may be possible at larger spatial scales or with stronger climatic or topographic variation. Our study shows that genetic analyses can differentiate the geographic origin of tropical timber at the scale of forest concessions, demonstrating their potential as forensic tools to enforce timber trade legislation.

AB - Combatting illegal timber trade requires forensic tools that independently verify claimed geographic origin of timber. Chemical and genetic wood characteristics are potentially suitable tools, but their performance at small spatial scales is unknown. Here we test whether stable isotopes and microsatellites can differentiate Tali timber (Erythrophleum spp.) at the level of forest concessions. We collected 394 wood samples from 134 individuals in five concessions in Cameroon and Congo Republic. The nearest neighbour concessions were 14 km apart and the furthest pair 836 km apart. We constructed genetic profiles using eight nuclear microsatellite markers and measured concentrations of δ18O, δ15N and δ13C. We differentiated provenances using PCA (microsatellites), ANOVA and kernel discriminant analysis (isotopes). Next, we performed assignment tests using blind samples (n = 12, microsatellites) and leave one out cross validation (LOOCV, isotopes). Isotopic composition varied strongly within concessions and only δ13C differed significantly between two concessions. As a result, LOOCV performed only marginally better than random. Genetic differentiation among provenances was also relatively low, but private alleles were commonly found. Bayesian clustering analysis correctly assigned 92% of the blind samples, including those of nearby concessions. Thus, Tali timber can be successfully assigned to the concession of origin using genetic markers, but not using isotopic composition. Isotopic differentiation may be possible at larger spatial scales or with stronger climatic or topographic variation. Our study shows that genetic analyses can differentiate the geographic origin of tropical timber at the scale of forest concessions, demonstrating their potential as forensic tools to enforce timber trade legislation.

KW - DNA

KW - Geographic origin

KW - Microsatellites

KW - Stable isotopes

KW - Timber forensics

KW - Tropical timber

U2 - 10.1016/j.biocon.2018.01.031

DO - 10.1016/j.biocon.2018.01.031

M3 - Article

VL - 220

SP - 262

EP - 271

JO - Biological Conservation

JF - Biological Conservation

SN - 0006-3207

ER -