Data from: Genetic resources of teak (Tectona grandis Linn. f.) – strong genetic structure among natural populations

Twenty-nine provenances of teak (Tectona grandis Linn. f.) representing the full natural distribution range of the species were genotyped with microsatellite DNA markers to analyse genetic diversity and population genetic structure. Provenances originating from the semi-moist east coast of India had the highest genetic diversity while provenances from Laos showed the lowest. In the eastern part of the natural distribution area, comprising Myanmar, Thailand and Laos, there was a strong clinal decrease in genetic diversity the further east the provenance was located. Overall, the pattern of genetic diversity supports the hypothesis that teak has its centre of origin in India, from where it spread eastwards. The analysis of molecular variance (AMOVA) gave an overall highly significant F st value of 0.227—population pairwise F st values were in the range 0.01–0.48. Applying the G″st differentiation parameter, the estimated overall differentiation was 0.632, implying a strong genetic structure among populations. A neighbour-joining (NJ) tree, using the pairwise population matrix of G″st values as input, contained three distinct groups: (1) the eight provenances from Thailand and Laos, (2) the Indian provenances from the dry interior and the moist west coast and (3) the provenances from northern Myanmar. The provenances from southern Myanmar were placed close to the root of the tree together with the three provenances from the semi-moist east coast of India. A Bayesian cluster analysis using the STRUCTURE software gave very similar results, with three main clusters, each containing two sub-clusters, while Bayesian cluster analysis in the Geneland software, exploiting the spatial coordinates of the provenances, resulted in five clusters in accordance with the former results. The implications of the findings for conservation and use of genetic resources of the species are discussed.

本研究以覆盖柚木（Tectona grandis Linn. f.）完整自然分布范围的29个种源为材料，采用微卫星DNA标记进行基因分型，以解析其遗传多样性与群体遗传结构。结果显示，源自印度半湿润东海岸的种源遗传多样性最高，而老挝种源的遗传多样性最低。在包含缅甸、泰国与老挝的自然分布区东部，种源越往东，遗传多样性呈现显著的梯度下降趋势。总体而言，该遗传多样性分布格局支持柚木起源中心位于印度、并向东扩散的假说。分子方差分析（Analysis of Molecular Variance, AMOVA）得到整体极显著的Fst值为0.227——群体间两两Fst值介于0.01至0.48之间。采用G″st分化参数估算得到整体分化水平为0.632，表明群体间存在较强的遗传结构。以G″st值的群体间两两矩阵为输入构建的邻接（Neighbour-Joining, NJ）系统发育树共分为3个显著类群：① 来自泰国与老挝的8个种源；② 来自印度干旱内陆与湿润西海岸的种源；③ 来自缅甸北部的种源。缅甸南部种源与印度半湿润东海岸的3个种源一同位于系统发育树的近根部位置。采用STRUCTURE软件进行的贝叶斯聚类分析得到了高度一致的结果：共划分3个主簇，每个主簇又包含2个亚簇；而利用种源空间坐标的Geneland软件贝叶斯聚类分析则得到5个簇，与前述结果相符。本研究最后探讨了上述发现对该物种遗传资源保护与利用的启示。