We identified both the fungi and plants of ectomycorrhizal root tips of Dipterocarpaceae using the sequence of mitochondrial large (ML) subunit ribosomal DNA, internal transcribed spacer (ITS) sequence of nuclear ribosomal DNA, partial matK sequence of chloroplast DNA and trnL-trnF spacer sequence of chloroplast DNA. We compared the DNA sequences from ectomycorrhizal roots with the sequences from the available databases using phylogenetic analysis. The ectomycorrhizal fungi identified by ML and/or ITS sequences belonged to the following seven families: Russulaceae, Boletaceae, Cortinariaceae, Thelephoraceae, Hygrophoraceae, Sclerodermataceae, Cantharellaceae and Amanitaceae. The Dipterocarpaceae species identified by partial matK and/or trnL-trnF sequences belonged to the following genera: Dryobalanops, Hopea, Vatica, Cotylelobium, Anisoptera, Upuna, Dipterocarpus and Shorea. Members of Thelephoraceae, which have never been reported to form symbiotic roots with Dipterocarpaceae, appeared to be the most abundant and were usually associated with Shorea species. Analyses of other Dipterocarpaceae species are needed to confirm these results.

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The Dipterocarpaceae, a well-known tropical tree family of Asian rainforests, is the most dominant component of Sri Lankan rainforests. The origin of Sri Lankan Dipterocarpaceae and their relationship with other Asian members of the family are still unknown. We studied this relationship using chloroplast DNA nucleotide sequences. DNA sequences of trnL-trnF spacer and trnL intron regions from 27 Sri Lankan species, and 62 other species belonging to 14 genera were included in the study. The neighbor joining (NJ) tree was constructed using aligned sequences of both regions. Monotes madagascariensis was used as an out-group. The obtained result is, to a certain extent, consistent with the current morphology based on taxonomy of Dipterocarpaceae. The Sri Lankan endemic genus Stemonoporus formed a monophyletic clade. The other Sri Lankan species of Hopea, Dipterocarpus, Vatica, Cotylelobium, Vateria and most of Shorea formed separate groups on the phylogenetic tree. This may indicate that Sri Lankan Dipterocarpaceae evolved independently after Sri Lanka became geographically isolated from the Indo- Malaysian region.

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Very little is known about the levels and patterns of DNA polymorphism in populations of tropical trees. In this study, we investigated population genetic structure of the four following Shorea species: Shorea acuminata, S. curtisii, S. leprosula and S. parvifolia from peninsular Malaysia using DNA sequences of Glyceraldehyde-3-phosphate dehydrogenase nuclear gene (GapC). The average nucleotide diversities of the investigated species for silent sites (π_sil= 0.0027) were lower than those reported for herbaceous plants, and similar or somewhat lower than those of other woody species. These low levels of nucleotide diversities may be caused by small effective population size of Shorea species. We found that some individuals harbored atypical haplotypes consisting of sequences from two different species. The segmented architecture of these haplotypes suggests past inter-specific gene exchange and fertility of the hybrids. As demonstrated in this study analysis of DNA sequences provides genetic evidence for the occurrence of inter-specific hybridization and gives important insights into its evolutionary effects.

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Recent understanding on biparental inbreeding depression teaches us that pollen relatedness to female gametes should be regarded as a significant aspect of pollen quality. Pollen relatedness is determined by pollen dispersal pattern and spatial genetic structure, however the former is possibly affected to varying degrees by certain variations in pollination conditions. Our recent study, which applied DNA microsatellite markers to study pollen dispersal patterns and pollen relatedness in a tropical emergent tree in two years, showed that the level of inbreeding differed affected by different types of pollinators. This infers that pollen of good quality dispersed under a particular pollination condition may play a significant role in population regeneration. Relationships between pollen dispersal patterns and various reproductive traits or conditions should be elucidated to better understand plant reproductive strategies.

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To clarify the present state of genetic differentiation among local honey bees (Apis cerana, A. koschevnikovi and A. dorsata) living in Borneo, we conducted phylogenetic analyses of specimens using the mitochondrial cytochrome oxidase subunit 1 (CO1) sequences. The results confirmed previous findings that genetic differentiation among local groups of A. koschevnikovi was much greater than among A. cerana and A. dorsata. Moreover, the phylogeographic analysis divided A. koschevnikovi into three distinct groups in the areas studied, which contrasts with the current biogeographic divisions of Borneo. In addition, a past colonization of A. cerana from Java to the southern part of Kalimantan was suggested.

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Phylogenetic relationships of evergreen Fagaceae species mainly distributed in Japan and Malaysia were examined based on chloroplast DNA sequences. In the genus Castanopsis and Lithocalpus, Japanese and Malaysian species formed separate clusters, but are monophyletic. Whereas for the Quercus subgenus Cyclobalanopsis, Japanese and Malaysian species clustered in separate groups and were not monophyletic. The Southeast Asian endemic species Trigonobalanus verticillata maintained a large inter-populational genetic variation which is similar to the level among species within genus, suggesting it was isolated for a long time in primitive state. The molecular clock approach showed that intra-generic diversifications between the monophyletic groups of Japanese and Malaysian taxa within Castanopsis, Lithocarpus and Cyclobalanopsis occurred by 22 - 17 MYA (Early to Middle Miocene). The distinct phylogenetic patterns between Japanese and Malaysian taxa suggest that the temperate to tropical disjunction in Asia might be the result of the long-term isolation of these evergreen genera, which was probably caused by the withdrawal and subdivision of the forests following the change to a moist and warm climate in Middle Miocene.

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A “gene-data bank” of tropical rainforest tree species in Sarawak was constructed. This work was initiated to deposit DNA materials from tree species in the whole area of Sarawak and found the information gathered to be effective tools for the sustainable management of bio-resources. For this study leaf samples, mainly from dipterocarp species, were collected from eight natural populations in national parks mainly and also several man-made forests. We collected nearly 5,000 samples including 127species in 27 families. DNA extraction was done in the Forest Research Centre (FRC) in Kuching, Sarawak using a modified CTAB method. These DNA samples were deposited along with field sampling data and DNA extraction data. Genetic analysis using RAPD, AFLP, microsatellite and DNA sequencing is now under progress to clarify the genetic constitution of the tree populations. Genetic information obtained by these methods will be useful in specifying the individual trees and will be incorporated into the gene-data bank.

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The genetic relatedness of selected mother trees of Shorea leprosula (24 trees) and Dipterocarpus cornutus (10 trees) was investigated using four simple sequence repeats (SSRs) loci in two seed production areas, a 1 ha seed stand of S. leprosula and a 0.9 ha seed stand of D. cornutus in Compartment 17, Labis Forest Reserve, Segamat, Johor. A total of 24 and 32 saplings in the vicinity of selected mother trees of S. leprosula and D. cornutus, respectively was collected for parentage analysis. Based on SSR polymorphisms, four mother trees of S. leprosula (i.e. SM1, SM9, SM15 and SM21) and three mother trees of D. cornutus (i.e. DM2 or DM3, DM5 and DM8), are not closely related and therefore could be used as potential seed sources for an advanced breeding program. The mean genetic identity of the S. leprosula and D. cornutus mother trees was low (0.471 and 0.557, respectively). Low spatial genetic structure within the population of mother trees was detected in S. leprosula and D. cornutus. This implies that extensive gene flow occurred in these species within the seed production areas. This is validated in the present study for D. cornutus where only about 13.3% of alleles detected in saplings seemed to have originated from adult trees outside the forest seed production area (SPA).

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