Genetic differences among Cedrela odorata sites in Bolivia provide limited potential for fine-scale timber tracing
2019
Paredes-Villanueva, Kathelyn | de Groot, G Arjen | Laros, Ivo | Bovenschen, Jan | Bongers, Frans | Zuidema, Pieter A.
Illegal trade of tropical timber leads to biodiversity and economic losses worldwide. There is a need for forensic tools that allow tracing the origin of timber and verifying compliance with international and national regulations. We evaluated the potential for genetic tracing of Cedrela odorata, one of the most traded neotropical timbers, within Bolivia. Using a set of seven microsatellites (SSRs), we studied the spatial distribution and genetic diversity and tested whether populations show sufficient genetic discrimination for timber tracing at a national level. Cambium and leaves were sampled from 81 C. odorata trees from three sites, at 268–501-km distance. To explore genetic differentiation, Bayesian clustering and principal component analysis (PCA) were employed. To infer the origin of samples, we conducted kernel discriminant analysis (KDA) based on a PCA that included all alleles and a manual assessment of site-unique alleles. The PCA showed three distinct genetic clusters, but only one of them corresponded with one of the sampled sites. The KDA based on allele frequency had a 33.7% mean classification error, with a considerably lower error (8.2%) for the site which matched with one genetic cluster. The blind test on unique alleles led to a similar classification error (30%). The occurrence of multiple genetic clusters within sites suggests that Bolivian C. odorata populations contain several parental lines, resulting in limited potential for forensic tracing at a national level. Based on our findings, we recommend for additional sampling across the spatial range of C. odorata within the country to support the development of forensic techniques for this species.
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