The expanding urbanization of coastal areas has led to increased ocean sprawl, which has had both physical and chemical adverse effects on marine and coastal ecosystems. To maintain the health and functionality of these ecosystems, it is imperative to develop effective solutions. One such solution involves the use of biodegradable polymers as bioactive coatings to enhance the bioreceptivity of marine and coastal infrastructures. Our study aimed to explore two main objectives: (1) investigate PHA-degrading bacteria on polymer-coated surfaces and in surrounding seawater, and (2) comparing biofilm colonization between surfaces with and without the polymer coating. We applied poly(3-hydroxybutyrate) [P(3HB)) coatings on concrete surfaces at concentrations of 1% and 6% w/v, with varying numbers of coating cycles (1, 3, and 6). Our findings revealed that the addition of P(3HB) indeed promoted accelerated biofilm growth on the coated surfaces, resulting in an occupied area approximately 50% to 100% larger than that observed in the negative control. This indicates a remarkable enhancement, with the biofilm expanding at a rate roughly 1.5 to 2 times faster than the untreated surfaces. We observed noteworthy distinctions in biofilm growth patterns based on varying concentration and number of coating cycles. Interestingly, treatments with low concentration and high coating cycles exhibited comparable biofilm enhancements to those with high concentrations and low coating cycles. Further investigation into the bacterial communities responsible for the degradation of P(3HB) coatings identified mostly common and widespread strains but found no relation between the concentration and coating cycles. Nevertheless, this microbial degradation process was found to be highly efficient, manifesting noticeable effects within a single month. While these initial findings are promising, it's essential to conduct tests under natural conditions to validate the applicability of this approach. Nonetheless, our study represents a novel and bio-based ecological engineering strategy for enhancing the bioreceptivity of marine and coastal structures.
Nipah virus (NiV) encephalitis first reported in "Sungai Nipah" in Malaysia in 1999 has emerged as a global public health threat in the Southeast Asia region. From 1998 to 2018, more than 630 cases of NiV human infections were reported. NiV is transmitted by zoonotic (from bats to humans, or from bats to pigs, and then to humans) as well as human-to-human routes. Deforestation and urbanization of some areas have contributed to greater overlap between human and bat habitats resulting in NiV outbreaks. Common symptoms of NiV infection in humans are similar to that of influenza such as fever and muscle pain and in some cases, the inflammation of the brain occurs leading to encephalitis. The recent epidemic in May 2018 in Kerala for the first time has killed over 17 people in 7 days with high case fatality and highlighted the importance of One Health approach. The diagnosis is often not suspected at the time of presentation and creates challenges in outbreak detection, timely control measures, and outbreak response activities. Currently, there are no drugs or vaccines specific for NiV infection although this is a priority disease on the World Health Organization's agenda. Antivirals (Ribavirin, HR2-based fusion inhibitor), biologicals (convalescent plasma, monoclonal antibodies), immunomodulators, and intensive supportive care are the mainstay to treat severe respiratory and neurologic complications. There is a great need for strengthening animal health surveillance system, using a One Health approach, to detect new cases and provide early warning for veterinary and human public health authorities.
In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forests was attributed to global environmental change, such as an increase in atmospheric CO2 concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16-52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Aboveground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant (+0.24 MgC ha(-1) y(-1), 95% confidence intervals [0.07, 0.39] MgC ha(-1) y(-1)), but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (+0.33 [0.09, 0.55] % y(-1)) compared with the tree community as a whole (+0.15 % y(-1)); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (+0.21 [0.02, 0.37] % y(-1)), and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering from past disturbances and affected by changes in resource availability. More long-term studies are necessary to clarify the contribution of global change to the functioning of tropical forests.
Peat fires in tropical peatland release a substantial amount of carbon into the environment and cause significant harm to peatlands and the ecology, resulting in climate change, biodiversity loss, and the alteration of the ecosystem. It is essential to understand peat fires and to develop more effective methods for controlling them. To estimate carbon emissions and monitor fires, the depth of burning can measure the overall burnt down the volume, which is proportional to the carbon emissions that are emitted to the environment. The first step is to understand the technique of measuring the depth of the burn. However, there is a lack of integrated information regarding the burning depth for peat fires. This review paper discusses the techniques used to measure the burning depth, with particular attention given to quantifying carbon emissions. The article also provides information on the types of methods used to determine the burning depths. This research contributes to the field of peat fire by providing a readily available reference for practitioners and researchers on the current state of knowledge on peat fire monitoring systems.
Dengue fever (DF) is an urban vector-borne disease transmitted by Aedes aegypti and Aedes albopictus. Both species deposit their eggs in favorable breeding sites either in natural or artificial containers. An understanding of their habitat characteristics is crucial in curbing DF outbreaks
Multibeam echosounders (MBES) are increasingly becoming the tool of choice for marine habitat mapping applications. In turn, the rapid expansion of habitat mapping studies has resulted in a need for automated classification techniques to efficiently map benthic habitats, assess confidence in model outputs, and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth. However, studies that make use of the full range of MBES outputs within a single classification process are limited. We present an approach that integrates backscatter angular response with MBES bathymetry, backscatter mosaic and their derivatives in a classification process using a Random Forests (RF) machine-learning algorithm to predict the distribution of benthic biological habitats. This approach includes a method of deriving statistical features from backscatter angular response curves created from MBES data collated within homogeneous regions of a backscatter mosaic. Using the RF algorithm we assess the relative importance of each variable in order to optimise the classification process and simplify models applied. The results showed that the inclusion of the angular response features in the classification process improved the accuracy of the final habitat maps from 88.5% to 93.6%. The RF algorithm identified bathymetry and the angular response mean as the two most important predictors. However, the highest classification rates were only obtained after incorporating additional features derived from bathymetry and the backscatter mosaic. The angular response features were found to be more important to the classification process compared to the backscatter mosaic features. This analysis indicates that integrating angular response information with bathymetry and the backscatter mosaic, along with their derivatives, constitutes an important improvement for studying the distribution of benthic habitats, which is necessary for effective marine spatial planning and resource management.
Eicosapentaenoic acid (EPA) could be extracted from diatoms such as Amphora sp. present abundantly in the ecosystems. In view of the key environmental and nutritional factors governing the diatoms growth rate, culture conditions were optimized for the biomass yield, total lipid content, EPA yield, and fatty acid composition under two main cultivation regimes: photoautotrophic and heterotrophic. The fastest growth rate about 0.20 ± 0.02 g/L and the highest EPA yield about 9.19 ± 3.56 mg EPA/g biomass were obtained by adding 10 g/L glucose and sucrose, respectively. Under photoautotrophic culture conditions, Amphora sp. rendered higher EPA yield at 100 rpm and 16:8 light/dark cycle. Total fatty acids produced predominantly comprised of an approximate 40-70% of saturated fatty acids, followed by 10-27% of monounsaturated fatty acids and then 8-25% of polyunsaturated fatty acids. These findings were able to pave a way for huge-scale microalgal biomass production in commercial EPA production.
Cities all over the world are edging further into the ocean. Coastal reclamation is a global conservation issue with implications for ocean life, ecosystems, and human well-being. Using Malaysia as a case study, the coastal reclamation trends over three decades (1991-2021) were mapped using Landsat images and Normalized Difference Water Index (NDWI) via the Google Earth Engine platform. The changes in drivers and impacts of these coastal expansions throughout the decades were also reviewed. Twelve out of the 14 states in Malaysia had planned, active, or completed reclamations on their shorelines. Between 1991 and 2021, an absolute area of 82.64 km2 has been or will be reclaimed should all the projects be completed. The most reported driver for coastal expansion in Malaysia is for development and modernization (41 %), followed by rise in human population (20 %), monetary gains from the development of prime land (15 %), and agriculture and aquaculture activities (9 %). Drivers such as reduction of construction costs, financial advantage of prime land, oil and gas, advancement of technology, and tourism (Malaysia My Second Home (MM2H)) had only started occurring within the last decade, while others have been documented since the 1990's. Pollution is the most reported impact (24 %) followed by disruption of livelihoods, sources of income and human well-being (21 %), destruction of natural habitats (17 %), decrease in biodiversity (11 %), changes in landscapes (10 %), erosion / accretion (8 %), threat to tourism industry (6 %), and exposure to wave surges (3 %). Of these, changes in landscape, shoreline alignment, seabed contour, and coastal groundwater, as well as wave surges had only started to surface as impacts in the last two decades. Efforts to protect existing natural coastal and marine ecosystems, restore degraded ones, and fund endeavours that emphasize nature is needed to support sustainable development goals for the benefit of future generations.
Knowledge about the timing and synchrony of coral spawning has important implications for both the ecology and management of coral reef ecosystems. Data on the timing of spawning and extent of synchrony, however, are still lacking for many coral reefs, particularly from equatorial regions and from locations within the coral triangle. Here we present the first documentation of a multi-species coral spawning event from reefs around Pulau Tioman, Peninsular Malaysia, a popular diving and tourist destination located on the edge of the coral triangle. At least 8 coral species from 3 genera (Acropora, Montipora and Porites) participated in multi-species spawning over five nights in April 2014, between two nights before and two nights after the full moon. In addition, two Acropora species were witnessed spawning one night prior to the full moon in October 2014. While two of the Acropora species that reproduced in April (A. millepora and A. nasuta) exhibited highly synchronous spawning (100% of sampled colonies), two other common species (A. hyacinthus and A. digitifera) did not contain visible eggs in the majority of colonies sampled (i.e., <15% of colonies) in either April or October, suggesting that these species spawn at other times of the year. To the best of our knowledge, this is the first detailed documented observation of multi-species coral spawning from reefs in Malaysia. These data provide further support for the contention that this phenomenon is a feature of all speciose coral assemblages, including equatorial reefs. More research is needed, however, to determine the seasonal cycles and extent of spawning synchrony on these reefs and elsewhere in Malaysia.
Drought monitoring is crucial for assessing and mitigating the impacts of water scarcity on various sectors and ecosystems. Although traditional drought monitoring relies on soil moisture data, remote sensing technology has have significantly augmented the capabilities for drought monitoring. This study aims to evaluate the accuracy and applicability of two temperature vegetation drought indices (TVDI), TVDINDVI and TVDIEVI, constructed using the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) vegetation indices for drought monitoring. Using Guangdong Province as a case, enhanced versions of these indices, developed through Savitzky-Golay filtering and terrain correction were employed. Additionally, Pearson correlation analysis and F-tests were utilized to determine the suitability of the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) in correlation with TVDINDVI and TVDIEVI. The results show that TVDINDVI had more meteorological stations passing both significance test levels (P
This study reported the ant species that were recovered from monkey carcasses in three different ecological habitats in Malaysia. The study was conducted from 9 May - 10 October 2007, 6 May - 6 August 2008 and 26 May - 14 July 2009 in forested area (Gombak, Selangor), coastal area (Tanjong Sepat, Selangor) and highland area (Bukit Cincin, Pahang), respectively. Monkey carcass was used as a model for human decomposition in this study. A total of 4 replicates were used in each of the study sites. Ants were observed to prey on eggs, larvae, pupae and newly emerged flies. This study found that ant species could be found at all stages of decomposition, indicating that ants were not a significant indicator for faunal succession. However, different species of ants were obtained from monkey carcasses placed in different ecological habitats. Cardiocondyla sp. was only found on carcasses placed in the coastal area; while Pheidole longipes, Hypoponera sp. and Pachycondyla sp. were solely found on carcasses placed in the highland area. On the other hand, Pheidologeton diversus and Paratrechina longicornis were found in several ecological habitats. These data suggests that specific ant species can act as geographic indicators for different ecological habitats in forensic entomology cases in Malaysia.
Microplastic pollution is widely recognised as a global issue, posing risks to natural ecosystems and human health. The combination of rapid industrial and urban development and relatively limited environmental regulation in many tropical countries may increase the amount of microplastic entering rivers, but basic data on contamination levels are lacking. This is especially the case in tropical South East Asian countries. In this paper, the abundance, composition and spatio-temporal variation of microplastic in the Langat River, Malaysia, were assessed, and the relationship between microplastic concentration and river discharge was investigated. Water samples were collected over a 12-month period from 8 sampling sites on the Langat, extending from forested to heavily urbanised and industrial areas. All 508 water samples collected over this period contained microplastic; mean concentration across all sites and times was 4.39 particles/L but extended up to 90.00 particles/L in some urban tributaries. Most microplastics were secondary in origin, and dominated by fibres. Microplastic counts correlated directly with river discharge, and counts increased and decreased in response to changes in flow. A time-integrated assessment of the microplastic load conveyed by the Langat suggested that the river is typically (50 % of the time) delivering around 5 billion particles per day to the ocean. The positive correlation between the concentration of microplastics and suspended sediments in the Langat suggested that continuously logging turbidity sensors could be used to provide better estimates of microplastic loads and improve assessment of human and ecological health risks.
Plastics are synthetic polymers known for their outstanding durability and versatility, and have replaced traditional materials in many applications. Unfortunately, their unique traits ensure that they pose a major threat to the environment. While literature on freshwater microplastic contamination has grown over the recent years, research undertaken in rapidly developing countries, where plastic production and use are increasing dramatically, has lagged behind that in other parts of the world. In the South East Asia (SEA) region, basic information on levels of contamination is very limited and, as a consequence, the risk to human and ecological health remains hard to assess. This review synthesises what is currently known about microplastic contamination of freshwater ecosystems in SEA, with a particular focus on Malaysia. The review 1) summarises published studies that have assessed levels of contamination in freshwater systems in SEA, 2) discusses key sources and transport pathways of microplastic in freshwaters, 3) outlines what is known of the impacts of microplastic on freshwater organisms, and 4) identifies key knowledge gaps related to our understanding of the transport, fate and effects of microplastic.
Mutualistic and antagonistic plant-animal interactions differentially contribute to the maintenance of species diversity in ecological communities. Although both seed dispersal and predation by fruit-eating animals are recognized as important drivers of plant population dynamics, the mechanisms underlying how seed dispersers and predators jointly affect plant diversity remain largely unexplored. Based on mediating roles of seed size and species abundance, we investigated the effects of seed dispersal and predation by two sympatric primates (Nomascus concolor and Trachypithecus crepusculus) on local plant recruitment in a subtropical forest of China. Over a 26 month period, we confirmed that these primates were functionally distinct: gibbons were legitimate seed dispersers who dispersed seeds of 44 plant species, while langurs were primarily seed predators who destroyed seeds of 48 plant species. Gibbons dispersed medium-seeded species more effectively than small- and large-seeded species, and dispersed more seeds of rare species than common and dominant species. Langurs showed a similar predation rate across different sizes of seeds, but destroyed a large number of seeds from common species. Due to gut passage effects, gibbons significantly shortened the duration of seed germination for 58% of the dispersed species; however, for 54% of species, seed germination rates were reduced significantly. Our study underlined the contrasting contributions of two primate species to local plant recruitment processes. By dispersing rare species and destroying the seeds of common species, both primates might jointly maintain plant species diversity. To maintain healthy ecosystems, the conservation of mammals that play critical functional roles needs to receive further attention.
Microplastics (MPs) pose a threat to ecosystems due to their capacity to bind with toxic chemicals. While the occurrence of MPs in aquatic environmental matrices like water, sediments, and biota is well studied, their presence in the atmosphere remains less understood. This study aimed to determine the presence of airborne MPs and their characteristics through ground-based sampling in the coastal city of Kuala Nerus, Terengganu, Malaysia. Airborne MP samples were collected using passive sampling technique in December 2019. MPs were manually counted and identified using a stereomicroscope based on their colour and shape. The average deposition rate of airborne MPs during the sampling period was 5476 ± 3796 particles/m2/day, ranging from 576 to 15,562 particles/m2/day. Various colours such as transparent (38%), blue (25%), black (20%), red (13%), and others (4%) were observed. The predominant shape of airborne MPs was fibres (> 99%). The morphology structure of MPs observed using a scanning electron microscope (SEM) showed a cracked surface on MPs, suggesting weathering and irregular fragmentation. Further elemental analysis using energy dispersive X-ray spectroscopy (EDS) showed the presence of heavy metals such as aluminium (Al) and cadmium (Cd) on the surface of MPs, attributed to the adsorption capacities of MPs. Polymer types of airborne MPs were analysed using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), which revealed particles composed of polyester (PES), polyethylene (PE), and polypropylene (PP). The preliminary findings could provide additional information for further investigations of MPs, especially in the atmosphere, to better understand their sources and potential human exposure.
Coptotermes gestroi (Wasmann) or the Asian subterranean termite is a serious structural pest in urban settlements in Southeast Asia that has been introduced to other parts of the world through human commerce. Although mitochondrial DNA markers were previously used to shed light on the dispersal history of the Asian subterranean termite, there were limited attempts to analyze or include populations of the termite found in the wild in Southeast Asia. In this study, we analyzed the 16S ribosomal RNA (16S rRNA) and cytochrome c oxidase subunit 1 (cox1) genes of Asian subterranean termite colonies found in mangrove swamps, beach forests, plantations, and buildings in semi-urban and urban areas to determine the relationship between colonies found in the wild and the urban habitat, and to investigate the possibility of different ecotypes of the termite in Peninsular Malaysia. Our findings show that the 16S rRNA haplotypes recovered from this study clustered into eastern, western, and southern populations of the termite, while the cox1 haplotypes were often specific to an area or site. The 16S rRNA and cox1 genes or haplotypes showed that the most abundant haplotype occupied a wide range of environments or habitats. In addition, the cox1 tree showed evidence of historical biogeography where basal haplotypes inhabited a wide range of habitats, while apical haplotypes were restricted to mangrove swamps and beach forests. Information on the haplotype-habitat association of C. gestroi will enable the prediction of habitats that may harbor or be at risk of invasion in areas where they have been introduced.
Samples of mangrove snails Nerita lineata and surface sediments were collected from nine geographical sampling sites in Peninsular Malaysia to determine the concentrations of eight metals. For the soft tissues, the ranges of metal concentrations (μg g(-1) dry weight (dw)) were 3.49-9.02 for As, 0.69-6.25 for Cd, 6.33-25.82 for Cu, 0.71-6.53 for Cr, 221-1285 for Fe, 1.03-50.47 for Pb, and 102.7-130.7 for Zn while Hg as 4.00-64.0 μg kg(-1) dw(-1). For sediments, the ranges were 21.81-59.49 for As, 1.11-2.00 for Cd, 5.59-28.71 for Cu, 18.93-62.91 for Cr, 12973-48916 for Fe, 25.36-172.57 for Pb, and 29.35-130.34 for Zn while for Hg as 2.66-312 μg kg(-1) dw(-1). To determine the ecological risks on the surface habitat sediments, sediment quality guidelines (SQGs), the geochemical indices, and potential ecological risk index (PERI) were used. Based on the SQGs, all the metals investigated were most unlikely to cause any adverse effects. Based on geoaccumulation index and enrichment factor, the sediments were also not polluted by the studied metals. The PERI values based on As, Cd, Cu, Cr, Hg, Pb and Zn in this study were found as 'low ecological risk'. In order to assess the potential health risks, the estimated daily intakes (EDI) of snails were found to be all lower than the RfD guidelines for all metals, except for Pb in some sites investigated. Furthermore, the calculated target hazard quotients (THQ) were found to be less than 1. However, the calculated total target hazard quotients (TTHQ) from all sites were found to be more than 1 for high level consumers except KPPuteh. Therefore, moderate amount of intake is advisable to avoid human health risks to the consumers.
Background. Climate change concurrent with anthropogenic disturbances can initiate serial changes that reverberate up the food chain with repercussions for fisheries. To date, there is no information available concerning the combined effects of global warming and human impacts on tropical marine food webs. While temperate copepods respond differently to warming and environmental stressors, the extent to which tropical copepods can adapt to rising temperature of already warm waters remains unknown. We hypothesize that sea warming and other anthropogenic disturbances over the long term will have the greatest impact on the copepod community in nearshore waters where their effects are accentuated, and therefore vulnerable and resilient species could be identified. Methods. Zooplankton samples were collected during two time periods (1985-86 and 2014-15) interposed by marked anthropogenic disturbances, and at the same five stations located progressively from inshore to offshore in Klang Strait, Malaysia, following the asymmetrical before-after-control-impact (BACI) design. Copepods were identified to species, and results were interpreted by univariate (ANOVA) and multivariate (PERMANOVA, PCO) analyses of the computed species abundance and diversity measures. Results. Copepod total abundance was not significantly different among stations but higher after disturbance than before disturbance. However, changes in the abundance of particular species and the community structure between time periods were dramatic. Coastal large-bodied calanoid species (e.g., Acartia spinicauda, Calanopia thompsoni, Pseudodiaptomus bowmani and Tortanus forcipatus) were the most vulnerable group to disturbance. This however favored the opportunistic species (e.g., Oithona simplex, O. attenuata, Hemicyclops sp., Pseudomacrochiron sp. and Microsetella norvegica). Small-bodied copepods (e.g., Paracalanus sp., Parvocalanus crassirostris and Euterpina acutifrons) were unaffected. Centropages tenuiremis was likely an introduced species. There was no significant loss in species richness of copepods despite the dramatic changes in community structure. Discussion. Sea warming and other human-induced effects such as eutrophication, acidification and coastal habitat degradation are likely the main factors that have altered copepod community structure. The large-bodied estuarine and coastal calanoid copepods are surmised to be vulnerable to eutrophication and hypoxia, while both resilient and opportunistic species are largely unaffected by, or adaptable to, degraded coastal environments and observed sea surface temperature (SST) rise. It is forecasted that SST rise with unmitigated anthropogenic impacts will further reduce large-bodied copepod species the favoured food for fish larvae with dire consequences for coastal fish production.
The canopies and roots of seagrass, mangrove, and saltmarsh protect a legacy of buried sedimentary organic carbon from resuspension and remineralisation. This legacy's value, in terms of mitigating anthropogenic emissions of CO2, is based on total organic carbon (TOC) inventories to a depth likely to be disturbed. However, failure to subtract allochthonous recalcitrant carbon overvalues the storage service. Simply put, burial of oxidation-resistant organics formed outside of the ecosystem provides no additional protection from remineralisation. Here, we assess whether black carbon (BC), an allochthonous and recalcitrant form of organic carbon, is contributing to a significant overestimation of blue carbon stocks. To test this supposition, BC and TOC contents were measured in different types of seagrass and mangrove sediment cores across tropical and temperate regimes, with different histories of air pollution and fire together with a reanalysis of published data from a subtropical system. The results suggest current carbon stock estimates are positively biased, particularly for low-organic-content sandy seagrass environs, by 18 ± 3% (±95% confidence interval) and 43 ± 21% (±95% CI) for the temperate and tropical regions respectively. The higher BC fractions appear to originate from atmospheric deposition and substantially enrich the relatively low TOC fraction within these environs.
Vivipary with precocious seedlings in mangrove plants was thought to be a hindrance to long-range dispersal. To examine the extent of seedling dispersal across oceans, we investigated the phylogeny and genetic structure among East Asiatic populations of Kandelia candel based on organelle DNAs. In total, three, 28 and seven haplotypes of the chloroplast DNA (cpDNA) atpB-rbcL spacer, cpDNA trnL-trnF spacer, and mitochondrial DNA (mtDNA) internal transcribed spacer (ITS) were identified, respectively, from 202 individuals. Three data sets suggested consistent phylogenies recovering two differentiated lineages corresponding to geographical regions, i.e. northern South-China-Sea + East-China-Sea region and southern South-China-Sea region (Sarawak). Phylogenetically, the Sarawak population was closely related to the Ranong population of western Peninsula Malaysia instead of other South-China-Sea populations, indicating its possible origin from the Indian Ocean Rim. No geographical subdivision was detected within the northern geographical region. An analysis of molecular variance (AMOVA) revealed low levels of genetic differentiation between and within mainland and island populations (phiCT = 0.015, phiSC = 0.037), indicating conspicuous long-distance seedling dispersal across oceans. Significant linkage disequilibrium excluded the possibility of recurrent homoplasious mutations as the major force causing phylogenetic discrepancy between mtDNA and the trnL-trnF spacer within the northern region. Instead, relative ages of alleles contributed to non-random chlorotype-mitotype associations and tree inconsistency. Widespread distribution and random associations (chi2 = 0.822, P = 0.189) of eight hypothetical ancestral cytotypes indicated the panmixis of populations of the northern geographical region as a whole. In contrast, rare and recently evolved alleles were restricted to marginal populations, revealing some preferential directional migration.