Digestion experiment
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Research Interests: Botany, Embryology, Reproduction, Plant Biology, Biology, and 9 moreAnatomy, Microspore Culture, Flora, Meiosis, Gametophyte, Sporangium, Gametogenesis, ovum, and ovule
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Birds are one of the most cost-effective groups to survey for monitoring human impacts on faunal communities and are consequently the best studied taxonomic group in urban areas. Urban bird assemblages are typically dominated by a few... more
Birds are one of the most cost-effective groups to survey for monitoring human impacts on faunal communities and are consequently the best studied taxonomic group in urban areas. Urban bird assemblages are typically dominated by a few pest species, and need to be appropriately managed to reduce the aesthetic costs and health risks they may pose in highly-populated areas. Studies were conducted in Singapore (Feb.2000 to Feb.2001) to provide recommendations to manage urban birds, in particular to control the population of two invasive alien bird species: the house crow (Corvus splendens) and the Javan myna (Acridotheres javanicus). We then re-surveyed the same sites 9 years later (Mar.2010 to Feb.2011) to compare the changes in the abundance of the 20 most common urban bird species in Singapore over the past decade. We also tested whether the decrease in house crow abundance was correlated with increases in abundance of its co-invasive, the Javan myna, or with the Asian koel (Eudynamys scolopacea), a brood parasite of the house crow, across sites. In addition, we investigated competition between two myna species by comparing whether declines in the abundance of the common myna (Acridotheres trista) were correlated with increases in the abundance of the Javan myna. Our results showed that a total of 14 species recorded a signifi cant increase in abundance between the two surveys, two species signifi cantly decreased, and four species had no signifi cant change. There was also no signifi cant correlation between all the bird abundances, although changes in bird abundances were signifi cantly associated with certain changes in the urban environment such as spontaneous or cultivated green cover. We suggest that reduced density of house crow nests may actually result in increased vulnerability to, and hence success rate of, brood parasitism by the Asian koel, or there may be increased parasitism of other host species' nests. Meanwhile, competitive effects among the other birds may not be detectable at the scale of the transects used in our study.
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Research Interests: Chemistry, Phytochemistry, Malaysia, Indonesia, NMR Spectroscopy, and 15 moreMedicinal Plants, Magnetic Resonance Spectroscopy, Medicine, Biological Sciences, High Pressure Liquid Chromatography, CHEMICAL SCIENCES, Glycerol, Isolation, Ferulic Acid, Chemical Structure, Lignan, Carbohydrate Sequence, Molecular Sequence Data, Celastraceae, and Medical and Health Sciences
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Abstract Extraction of the branches of Garcinia dulcis afforded a xanthone with a novel oxygenation pattern [1, 4, 6-trihydroxy-5-methoxy-7-(3-methylbut-2-enyl) xanthone] in addition to the triterpenoid friedelin and the known flavonoids... more
Abstract Extraction of the branches of Garcinia dulcis afforded a xanthone with a novel oxygenation pattern [1, 4, 6-trihydroxy-5-methoxy-7-(3-methylbut-2-enyl) xanthone] in addition to the triterpenoid friedelin and the known flavonoids 3′-(3-methylbut-2-enyl) ...
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ABSTRACTClusters of four circular forest plots, 0.2 ha in total area, were inventoried for canopy tree (≥30 cm gbh) and terrestrial herb floristic composition at 46 sites in the Central Catchment Nature Reserve, Singapore. The Nature... more
ABSTRACTClusters of four circular forest plots, 0.2 ha in total area, were inventoried for canopy tree (≥30 cm gbh) and terrestrial herb floristic composition at 46 sites in the Central Catchment Nature Reserve, Singapore. The Nature Reserve covers a complex mosaic of lowland tropical forest of different successional stages, with much of the area covered in secondary forest 50–100 years old developed on exhausted agricultural soils. A total of 449 species of tree and 59 species of terrestrial herb were recorded from the clusters. Facultatively-terrestrial epiphytes were excluded from the analysis. Possible reasons for the low herb diversity are discussed. There was a marked similarity between ordinations (detrended correspondence analysis) of the clusters based on tree canopy composition weighted by species relative contribution to cluster total basal area and the herb flora composition, with a highly significant correlation between first axis scores of the two ordinations. Both ord...
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Aim The primary objective of our study was to examine the factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands to understand how different groups of organisms with distinct... more
Aim The primary objective of our study was to examine the factors affecting the distribution of vascular plants, springtails, butterflies and birds on small tropical islands to understand how different groups of organisms with distinct biological traits respond to biogeographical variables, such as island area.
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A heath community found on Pulau Sibu, an island lying off the east coast of Peninsular Malaysia, was found to consist of a low scrub, generally under 2 m in height, containing 24 species of vascular plants growing on hills overlooking... more
A heath community found on Pulau Sibu, an island lying off the east coast of Peninsular Malaysia, was found to consist of a low scrub, generally under 2 m in height, containing 24 species of vascular plants growing on hills overlooking the sea. It grew on a very shallow and acidic (pH 4.3) soil that was low in total nitrogen concentration (0.2%). Leaves of the seven most common shrub species, Ixonanthes reticulata. Melastoma malabathricum, Rhodamnia cinerea, Rhodomyrtus tomentosa, Schima wallichii. Styphelia malayana and ...
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The fluids of pitcher plants are habitats to many specialized animals known as inquilines, which facilitate the conversion of prey protein into pitcher-absorbable nitrogen forms such as ammonium. (Diptera: Mycetophilidae) is a predatory... more
The fluids of pitcher plants are habitats to many specialized animals known as inquilines, which facilitate the conversion of prey protein into pitcher-absorbable nitrogen forms such as ammonium. (Diptera: Mycetophilidae) is a predatory dipteran inquiline that inhabits the pitchers of Larvae of construct sticky webs over the fluid surface of to ensnare emerging adult dipteran inquilines. However, the interaction between and its host has never been examined before, and it is not known if can contribute to nutrient sequestration in individuals were reared in artificial pitchers in the laboratory on a diet of emergent mosquitoes, and the ammonium concentration of the pitcher fluids was measured over time. Fluid ammonium concentration in tubes containing was significantly greater than those of the controls. Furthermore, fluid ammonium concentrations increased greatly after larvae metamorphosed, although the cause of this increase could not be identified. Our results show that a terrestr...
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The neural constraint hypothesis is central to understanding decision-making by foraging herbivorous insects which make decisions less efficiently when they face multiple choices for numerous resource types and/or at high densities... more
The neural constraint hypothesis is central to understanding decision-making by foraging herbivorous insects which make decisions less efficiently when they face multiple choices for numerous resource types and/or at high densities instead of a fewer choices. Previous studies have also shown the relationship between personality type and decision-making style. How personality types correlate with foraging efficiency among herbivores is however, largely untested. To answer this question, we used a widespread, polyphagous, floriphilic katydid, Phaneroptera brevis (Orthoptera: Tettigoniidae) and two naturalised, Asteraceae, food plants, Bidens pilosa and Sphagneticola trilobata, as model systems. After we determined each katydid's exploration and boldness levels, we examined its foraging efficiency across different combinations of floral resource choice and density. We showed: (1) For the first time within the Tettigonioidea lineage that this katydid exhibits different personality t...
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Asian tropical forests are under extreme stress from clearance, fragmentation, and logging. Because Singapore suffered these same impacts in the 19th century, it can act as an early warning system for the region. We identified invasive... more
Asian tropical forests are under extreme stress from clearance, fragmentation, and logging. Because Singapore suffered these same impacts in the 19th century, it can act as an early warning system for the region. We identified invasive exotic tree species from a comprehensive survey, assessed their survival and growth in the open and under a forest canopy, and compared their traits with native pioneers and widely planted exotic species that have failed to naturalize. Nine species were invasive: Acacia auriculiformis (ear-leaf acacia), Cecropia pachystachya (trumpet tree), Falcataria moluccana (Moluccan albizia), Leucaena leucocephala (leucaena), Manihot carthaginensis subp. glaziovii (Ceara rubber tree), Muntingia calabura (Jamaican cherry tree), Piper aduncum (spiked pepper), Pipturus argenteus (white mulberry), and Spathodea campanulata (African tulip tree). Under the forest canopy, all grew little and suffered high (75–100%) mortality, with Spathodea surviving best. At the open s...
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The study of the chemical constituents of branches and twigs of Cratoxylum cochinchinense collected in Singapore led to the isolation and structural elucidation of four new xanthones, named cratoxanthone A (1), B (2), C (3), and D (4),... more
The study of the chemical constituents of branches and twigs of Cratoxylum cochinchinense collected in Singapore led to the isolation and structural elucidation of four new xanthones, named cratoxanthone A (1), B (2), C (3), and D (4), together with six known xanthones (5-10) and one known dihydroanthracenone (11). Eight xanthones (including 1 and 2) and 11 were tested for their antiproliferative activity in three human carcinoma cell lines (lung adenocarcinoma A549, colorectal carcinoma Colo205, and epidermoid carcinoma KB) and a human acute lymphoblastic leukemia B cell line (NALM-6), and the mitochondrial membrane potential was determined in KB cells. New xanthones 1 and 2 attenuated NALM-6 cell proliferation with IC50 values of 17.78 and 8.27 µM, respectively. Furthermore, KB cells treated with these compounds had significantly decreased mitochondrial membrane potentials. Notably, the proliferation of A549 cells was specifically inhibited by 11, but not the xanthones.
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Gasification is recognized as a green technology as it can harness energy from biomass in the form of syngas without causing severe environmental impacts, yet producing valuable solid residues that can be utilized in other applications.... more
Gasification is recognized as a green technology as it can harness energy from biomass in the form of syngas without causing severe environmental impacts, yet producing valuable solid residues that can be utilized in other applications. In this study, the feasibility of co-gasification of woody biomass and food waste in different proportions was investigated using a fixed-bed downdraft gasifier. Subsequently, the capability of biochar derived from gasification of woody biomass in the rehabilitation of soil from tropical secondary forests on degraded land (adinandra belukar) was also explored through a water spinach cultivation study using soil-biochar mixtures of different ratios. Gasification of a 60:40 wood waste-food waste mixture (w/w) produced syngas with the highest lower heating value (LHV) 5.29 MJ/m(3)-approximately 0.4-4.0% higher than gasification of 70:30 or 80:20 mixtures, or pure wood waste. Meanwhile, water spinach cultivated in a 2:1 soil-biochar mixture exhibited the best growth performance in terms of height (a 4-fold increment), weight (a 10-fold increment) and leaf surface area (a 5-fold increment) after 8 weeks of cultivation, owing to the high porosity, surface area, nutrient content and alkalinity of biochar. It is concluded that gasification may be an alternative technology to food waste disposal through co-gasification with woody biomass, and that gasification derived biochar is suitable for use as an amendment for the nutrient-poor, acidic soil of adinandra belukar.
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A proposal is made for Singaporeans to cultivate native plant species propagated from plants growing in Singapore’s wild areas (native plants from Singapore stock — NPSS) for parks, gardens, streetscapes and any other plantings in urban... more
A proposal is made for Singaporeans to cultivate native plant species propagated from plants growing in Singapore’s wild areas (native plants from Singapore stock — NPSS) for parks, gardens, streetscapes and any other plantings in urban areas, instead of utilizing exotic (non-native) ornamental species or even native species of non-Singaporean stock. There is a growing trend for to utilize native plants for gardens and landscapes especially in the more developed countries such as the USA and the EU, so this is not a new idea. Use of native species has many advantages. However, for land-scarce countries like Singapore, where development covers about 90.2% of the land area of the country, whatever nature reserves there are, may already be viewed as a luxury of space. To expand the area covered by nature reserves,
Vrydagzynea lancifolia Ridl. was presumed to be nationally extinct until the rediscovery of a single individual in Bukit Timah Nature Reserve on 29 Oct.2013. Three inflorescences were observed on a single plant, but there was no fruit... more
Vrydagzynea lancifolia Ridl. was presumed to be nationally extinct until the rediscovery of a single individual in Bukit Timah Nature Reserve on 29 Oct.2013. Three inflorescences were observed on a single plant, but there was no fruit set. There were no other individuals found in the vicinity. Conservation is necessary to ensure the continued survival of this species in Singapore. A conservation status of critically endangered is proposed for this species.