望天树学名研讨

经考证,新组合的望天树学名Ｓｈｏｒｅａ ｃｈｉｎｅｎｓｉｓ Ｈ．Ｚｈｕ ｃｏｍｂ．ｎｏｖ．是不合法的晚出同名,它的合法正确学名应为Ｓｈｏｒｈａ ｗａｎｇｔｉａｎｓｈｕｅａ Ｙ．Ｋ．Ｙａｎｇ ｅｔ Ｊ．Ｋ．Ｗｕ ｎｏｍ．ｎｏｖ．。对其进行订正的明确目的是：根据现行的《国际植物命名法规》的原则,规则,辅则和规程来解决分类及鉴定中可能被混淆的问题。     

Beetle pollination of Shorea parvifolia (section Mutica, Dipterocarpaceae) in a general flowering period in Sarawak, Malaysia

Pollination ecology of an emergent tree species, Shorea (section Mutica) parvifolia (Dipterocarpaceae), was studied using the canopy observation system in a lowland dipterocarp forest in Sarawak, Malaysia, during a general flowering period in 1996. Although the species has been reported to be pollinated by thrips in Peninsular Malaysia, our observations of flower visitors and pollination experiments indicated that beetles (Chrysomelidae and Curculionidae, Coleoptera) contributed to pollination of S. parvifolia in Sarawak. Beetles accounted for 74% of the flower visitors collected by net-sweeping, and 30% of the beetles carried pollen, while thrips accounted for 16% of the visitors, and 12% of the thrips carried pollen. The apical parts of the petals and pollen served as a reward for the beetles. Thrips stayed inside the flower almost continuously after arrival, and movements among flowers were rare. Fruit set was significantly increased by introduction of beetles to bagged flowers, but not by introduction of thrips. Hand-pollination experiments and comparison of fruit set in untreated, bagged, and open flowers suggested that S. parvifolia was mainly outbreeding.     

High abscission rates of damaged expanding leaves: field evidence from seedlings of a Bornean rain forest tree

Herbivore damage is known to cause the premature loss of mature leaves. However, the effects of herbivory on abscission during the early stages of leaf development remain unexplored, even though herbivores frequently prefer unlignified, immature leaves. In a field experiment, we removed 50% of the tissue from leaves at various stages of development on seedlings of Shorea hopeifolia (Dipterocarpaceae), a dominant rain forest tree in Indonesian Borneo. Four weeks following simulated herbivory, >88% of unlignified expanding leaves had been abscised, compared to only 20% of fully expanded, unlignified leaves and 0% of recently lignified, mature leaves. In a separate experiment over 9 wk, simulated herbivory did not increase abscission rates of mature leaves, even when 75% of leaf tissue was removed. Because most (58%) of S. hopeifolia seedlings under natural conditions had lost 1% or less of the tissue from their mature leaves, herbivore damage probably has little effect on the abscission of mature leaves. In contrast, the tendency for damaged expanding leaves to abscise may explain why 49% of S. hopeifolia seedlings had already lost their youngest leaf. If similar patterns occur in other species, herbivore attacks on developing leaves may contribute substantially to both leaf loss and the cumulative impact of herbivory on the growth and survival of whole plants.     

Genetic diversity within and among populations of Shorea leprosula Miq. and Shorea parvifolia Dyer (Dipterocarpaceae) in Indonesia detected by AFLPs

The genetic diversity within and among populations of Shorea leprosula and Shorea parvifolia from Indonesia was investigated using amplified fragment length polymorphisms (AFLPs). The results indicated that S. leprosula is genetically more variable than S. parvifolia. At the population level, a higher level of genetic diversity was revealed for S. leprosula with a percentage of polymorphic loci (PPL_p) of 53.32% and an expected heterozygosity (H _ep) of 0.16 in comparison with S. parvifolia showing PPL_p of 51.79% and H _ep of 0.14. At the species level, S. leprosula showed PPL_s of 92.86% and H _es of 0.21, while S. parvifolia showed PPL_s of 85.71% and H _es of 0.21. Genetic differentiation (G _st) indicated that 25 and 31% of total genetic diversity in S. leprosula and S. parvifolia, respectively, were attributed to the differences among populations. An analysis of molecular variance (AMOVA) at two hierarchical levels exhibited that most genetic variation resided within populations with proportion of 70.2% for S. leprosula and 66.2% for S. parvifolia. The AMOVA at three hierarchical levels performed for S. leprosula and S. parvifolia together revealed that the genetic difference between the two species was remarkably higher with a proportion of 44.1% than the differences within and among populations (38.1 and 17.8%, respectively). The genetic differentiation between islands was significant for S. leprosula but not for S. parvifolia. The observed genetic diversity agreed with the life history traits of Shorea species. Highly differentiating individual AFLP markers were found for each species, which will serve as diagnostic markers for the identification of wood of different species, from different islands and regions.     

Isolation and characterization of 20 microsatellite loci for an important tropical tree Shorea leprosula (Dipterocarpaceae) and their applicability to S. parvifolia

Shorea leprosula is an important timber tree in Southeast Asia. From a genomic library enriched for dinucleotide (CT) repeats, 20 polymorphic microsatellite markers were developed for this species. Polymorphism of these loci was evaluated in a sample of 24 adult individuals from a natural population. The number of alleles ranged from five to 15, and the observed heterozygosity ranged from 0.333 to 0.875. Probability of paternity exclusion, in the case where the mother is known, ranged from 0.285 to 0.784. These markers were also characterized for applicability in S. parvifolia; 16 loci were successfully cross‐amplified and showed high levels of polymorphism.     

Relative enhancement of photosynthesis and growth at elevated CO2 is greater under sunflecks than uniform irradiance in a tropical rain forest tree seedling

The survivorship of dipterocarp seedlings in the deeply shaded understorey of South‐east Asian rain forests is limited by their ability to maintain a positive carbon balance. Photosynthesis during sunflecks is an important component of carbon gain. To investigate the effect of elevated CO₂ upon photosynthesis and growth under sunflecks, seedlings of Shorealeprosula were grown in controlled environment conditions at ambient or elevated CO₂. Equal total daily photon flux density (PFD) (～7·7 mol m^?2 d^?1) was supplied as either uniform irradiance (～170 µmol m^?2 s^?1) or shade/fleck sequences (～30 µmol m^?2 s^?1/～525 µmol m^?2 s^?1). Photosynthesis and growth were enhanced by elevated CO₂ treatments but lower under flecked irradiance treatments. Acclimation of photosynthetic capacity occurred in response to elevated CO₂ but not flecked irradiance. Importantly, the relative enhancement effects of elevated CO₂ were greater under sunflecks (growth 60%, carbon gain 89%) compared with uniform irradiance (growth 25%, carbon gain 59%). This was driven by two factors: (1) greater efficiency of dynamic photosynthesis (photosynthetic induction gain and loss, post‐irradiance gas exchange); and (2) photosynthetic enhancement being greatest at very low PFD. This allowed improved carbon gain during both clusters of lightflecks (73%) and intervening periods of deep shade (99%). The relatively greater enhancement of growth and photosynthesis at elevated CO₂ under sunflecks has important potential consequences for seedling regeneration processes and hence forest structure and composition.     

Genetic Diversity of a Tropical Tree Species,Shorea leprosula Miq. (Dipterocarpaceae), in Malaysia: Implications for Conservation of Genetic Resources and Tree Improvement1

Genetic diversity and population genetic structure of Shorea leprosula was investigated using seven natural populations distributed throughout Peninsular Malaysia and one natural population from Borneo. The mean population and species level genetic diversity were exceptionally high (H_e= 0.369 ± 0.025 and 0.406 ± 0.070, respectively). Heterozygosity varied among populations, ranging from 0.326 to 0.400, with the highest values found in the populations from central Peninsular Malaysia. Correlations among ecological factors (longitude, latitude, and annual rainfall) were not significant (P > 0.05), indicating that these ecological variables were not responsible for the observed genetic differences among populations. The Bangi adult population exhibited a higher level of observed heterozygosity but lower fixation indices in comparison to its seedling population. All other seedling populations also showed positive fixation indices (f), indicating a general excess of homozygotes. This also may suggest selection against homozygotes between the seedling and adult stages. A low level of population differentiation was detected (G_ST= 0.117 with the Lambir population and GST= 0.085 without the Lambir population). Furthermore, gene flow (N_m) between populations was not significantly correlated with geographical distances for the populations within Peninsular Malaysia. Cluster analysis also did not reflect geographical proximity and gave little insight into the genetic relatedness of the populations. This may indicate that the populations sampled are part of a continuous population with fragmentation having occurred in the recent past.