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 ( 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 δO, δN and δC. We differentiated provenances using PCA (microsatellites), ANOVA and kernel discriminant analysis (isotopes). Next, we performed assignment tests using blind samples ( = 12, microsatellites) and leave one out cross validation (LOOCV, isotopes). Isotopic composition varied strongly within concessions and only δC 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.

中文翻译：

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开发非洲木材的法医工具：区域起源是通过遗传特征而非同位素特征来揭示的

打击非法木材贸易需要法医工具来独立验证所声称的木材地理来源。木材的化学和遗传特征是潜在合适的工具，但它们在小空间尺度上的表现尚不清楚。在这里，我们测试稳定同位素和微卫星是否可以在森林特许权水平上区分塔里木材（spp.）。我们从喀麦隆和刚果共和国五个特许经营地的 134 个人收集了 394 个木材样本。最近的相邻特许权相距 14 公里，最远的特许权相距 836 公里。我们使用八个核微卫星标记构建了遗传图谱，并测量了 δO、δN 和 δ13C 的浓度。我们使用 PCA（微卫星）、ANOVA 和核判别分析（同位素）来区分出处。接下来，我们使用盲样本（= 12，微卫星）进行分配测试，并留出一个交叉验证（LOOCV，同位素）。特许权内的同位素组成差异很大，两个特许权之间只有 δ13C 存在显着差异。因此，LOOCV 的表现仅略好于随机。种源间的遗传分化也相对较低，但常见等位基因。贝叶斯聚类分析正确分配了 92% 的盲样本，包括附近特许权的样本。因此，可以使用遗传标记，而不是使用同位素组成，成功地将大理木材指定为原产地。同位素分化可能在更大的空间尺度或更强的气候或地形变化下发生。我们的研究表明，遗传分析可以在森林特许权范围内区分热带木材的地理起源，证明其作为执行木材贸易立法的法医工具的潜力。