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.

Teak (Tectona grandis Linn. f.) is one of the major plantation timbers of the world. The species is native to India, Myanmar, Thailand and Laos in South East Asia but was translocated to several countries in Africa and Central and South America during the past century. Today, large areas of plantations are grown outside the species native range. It is speculated that genetic bottlenecks and founder effects combined with new selection pressures under new growing conditions have led to the formation of distinct landraces; this hypothesis is supported by results from international provenance tests. In the present study, we apply genetic markers to identify the likely origin of teak grown outside its native range and examine if the landraces show signs of reduced genetic diversity. We find large variation in the level of diversity among landraces, although not larger than that observed among native populations. We conclude that variation in the studied teak landraces probably reflects their areas of genetic origin rather than severe founder effects created during their introduction. The genetic data suggests that the studied landraces originated from either the semi-moist east coast of India, southern Myanmar or western Thailand. These results indicate that translocation of teak has mainly come from a certain part of the native distribution and that this did not include the widespread natural teak areas of southern, dry interior or western India or northern Myanmar.

The level of chloroplast DNA (cpDNA) diversity was estimated among individuals, populations, and geographic regions of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in British Columbia by analyzing restriction fragment length polymorphisms (RFLP) from 18 populations covering the three geographic regions (coast, transition zone, and interior). Four sets of pooled probes, consisting of four to eight cpDNA clones from lodgepole pine (Pinuscontorta Dougl. ex Loud.), were used as hybridization probes for RFLP analysis. Thirty cpDNA restriction fragments out of a total of 175 observed fragments were detected to be polymorphic in all four sets of hybridization probes. Sixteen haplotypes were characterized among all of the Douglas-fir populations. The transition region showed the highest level of total genetic diversity (0.853) and genetic diversity within populations (0.762) of the three regions. The highest degree of population differentiation was found in the interior region (0.193). A higher proportion of the genetic diversity was allocated within populations than among populations in all three regions. Only 11–19% (mean 14.6%) of the total genetic diversity within geographic regions is due to interpopulation genetic diversities. The distribution of cpDNA diversity in sampled B.C. Douglas-fir is concordant with a typical pattern for long-lived woody species as observed in allozyme studies.

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