Accelerating forest loss in Southeast Asian Massif in the 21st century: A case study in Nan Province,Thailand

Farmers are carving a new agricultural frontier from the forests in the Southeast Asian Massif (SAM) in the 21st century, triggering significant environment degradation at the local scale; however, this frontier has been missed by existing global land use and forest loss analyses. In this paper, we chose Thailand's Nan Province, which is located in the geometric center of SAM, as a case study, and combined high resolution forest cover change product with a fine‐scale land cover map to investigate land use dynamics with respect to topography in this region. Our results show that total forest loss in Nan Province during 2001–2016 was 66,072 ha (9.1% of the forest cover in 2000), and that the majority of this lost forest (92%) had been converted into crop (mainly corn) fields by 2017. Annual forest loss is significantly correlated with global corn price (p < 0.01), re‐confirming agricultural expansion as a key driver of forest loss in Nan Province. Along with the increasing global corn price, forest loss in Nan Province has accelerated at a rate of 2,616 ± 730 ha per decade (p < 0.01). Global corn price peaked in 2012, in which year annual forest loss also reached its peak (7,523 ha); since then, the location of forest loss has moved to steeper land at higher elevations. Spatially, forest loss driven by this smallholder agricultural expansion emerges as many small patches that are not recognizable even at a moderate spatial resolution (e.g. 300 m). It explains how existing global land use/cover change products have missed the widespread and rapid forest loss in SAM. It also highlights the importance of high‐resolution observations to evaluate the environmental impacts of agricultural expansion and forest loss in SAM, including, but not limited to, the impacts on the global carbon cycle, regional hydrology, and local environmental degradation.     

Southeast Asian biodiversity: an impending disaster

Southeast Asia has the highest relative rate of deforestation of any major tropical region, and could lose three quarters of its original forests by 2100 and up to 42% of its biodiversity. Here, we report on the current state of its biota and highlight the primary drivers of the threat of extinction now faced by much of the unique and rich fauna and flora of the region. Furthermore, the known impacts on the biodiversity of Southeast Asia are likely to be just the tip of the iceberg, owing to the paucity of research data. The looming Southeast Asian biodiversity disaster demands immediate and definitive actions, yet such measures continue to be constrained by socioeconomic factors, including poverty and lack of infrastructure. Any realistic solution will need to involve a multidisciplinary strategy, including political, socioeconomic and scientific input, in which all major stakeholders (government, non-government, national and international organizations) must participate.     

Zoogeography of the Southeast Asian Rotifera

The distribution and taxonomic composition of Rotifera in Southeast Asia is reviewed. For some countries, records are poor: Brunei, Cambodia and Laos are almost terra incognitafor rotifers (<10 taxa recorded), while the Thai rotifer fauna is the best documented (ca. 310 taxa on record). However, analysis of the available data is impeded by fuzzy taxonomy and the questionable reliability of many records. Most studies focus on the pelagic or littoral of freshwater habitats. Other habitats are largely ignored. Similarly, few studies deal comprehensively with illoricate Monogononta, sessile Flosculariacea and Collothecacea and, especially, Bdelloidea. The genera Lecane, Brachionus and Trichocerca are the best represented, with littoral taxa predominant. Fisheries-related studies dealing with highly productive pelagic environments tend to over report the contribution of Brachionus. Most taxa are thermophilic character, exemplified by the dominance of tropic-centred Lecaneand Brachionus. Some cold-water taxa have been recorded, but the relative climatological homogeneity of the region and low number of studies on high-altitude environments prevent the discrimination of clear latitudinal or altitudinal variation in the distribution of rotifers within Southeast Asia. The majority of Southeast Asian rotifers are widely distributed, including true cosmopolites and thermophilic taxa. There are several local or Oriental endemic Rotifera, mostly Lecane. The American Brachionus havanaensis and Keratella americana appear to have been introduced to the region. The taxonomy of some Rotifera described from the region is commented upon; Brachionus murphyiSudzuki is recognised as senior synonym of B. niwati Sanoamuang et al. (syn. nov.). Some cases of geographical and/or ecological vicariant species-pairs are suggested. The Southeast Asian rotifer fauna contains a sizeable fraction of taxa occurring in the tropical regions of the Old World, most of which also occur in tropical Australia or the Austro-Malayan region. A tropical Australasian faunal component is present, but consists of few taxa only. Hence, affinities between the rotifer fauna of the Ethiopian, Oriental and tropical Australian and Austro-Malayan regions are supported, rather than an affinity between the Indo-Asian or Indo-Malaysian and tropical Australian fauna.     

盆栽和方池——东南亚园林的印度线索

本文以东南亚园林中的两个常见元素—盆栽和方池为例,呈现了印度文明对东南亚园林的影响。在此基础上,通过案例呈现了东南亚园林的宗教和哲学内涵以及相应的常见造园手法。以此指出,东南亚园林不只是对中国、欧洲园林的模仿,其园林设计受印度影响较大,且有一以贯之的逻辑,并能够承载深刻的思想内涵     

Mitochondrial DNA diversity in Southeast Asian populations

In a previous study of Southeast Asian genetic variation, we characterized mitochondrial DNAs (mtDNAs) from six populations through high-resolution restriction fragment length polymorphism (RFLP) analysis. Our analysis revealed that these Southeast Asian populations were genetically similar to each other, suggesting they had a common origin. However, other patterns of population associations also emerged. Haplotypes from a major founding haplogroup in Papua New Guinea were present in Malaysia; the Vietnamese and Malaysian aborigines (Orang Asli) had high frequencies of haplogroup F, which was also seen in most other Southeast Asian populations; and haplogroup B, defined by the Region V 9-base-pair deletion, was present throughout the region. In addition, the Malaysian and Sabah (Borneo) aborigine populations exhibited a number of unique mtDNA clusters that were not observed in other populations. Unfortunately, it has been difficult to compare these patterns of genetic diversity with those shown in subsequent studies of mtDNA variation in Southeast Asian populations because the latter have typically sequenced the first hypervariable segment (HVS-I) of the control region (CR) sequencing rather than used RFLP haplotyping to characterize the mtDNAs present in them. For this reason, we sequenced the HVS-I of Southeast Asian mtDNAs that had previously been subjected to RFLP analysis, and compared the resulting data with published information from other Southeast Asian and Oceanic groups. Our findings reveal broad patterns of mtDNA haplogroup distribution in Southeast Asia that may reflect different population expansion events in this region over the past 50,000-5,000 years.     

Indian genetic heritage in Southeast Asian populations

The great ethnolinguistic diversity found today in mainland Southeast Asia (MSEA) reflects multiple migration waves of people in the past. Maritime trading between MSEA and India was established at the latest 300 BCE, and the formation of early states in Southeast Asia during the first millennium CE was strongly influenced by Indian culture, a cultural influence that is still prominent today. Several ancient Indian-influenced states were located in present-day Thailand, and various populations in the country are likely to be descendants of people from those states. To systematically explore Indian genetic heritage in MSEA populations, we generated genome-wide SNP data (using the Affymetrix Human Origins array) for 119 present-day individuals belonging to 10 ethnic groups from Thailand and co-analyzed them with published data using PCA, ADMIXTURE, and methods relying on f-statistics and on autosomal haplotypes. We found low levels of South Asian admixture in various MSEA populations for whom there is evidence of historical connections with the ancient Indian-influenced states but failed to find this genetic component in present-day hunter-gatherer groups and relatively isolated groups from the highlands of Northern Thailand. The results suggest that migration of Indian populations to MSEA may have been responsible for the spread of Indian culture in the region. Our results also support close genetic affinity between Kra-Dai-speaking (also known as Tai-Kadai) and Austronesian-speaking populations, which fits a linguistic hypothesis suggesting cladality of the two language families.     

Amphibian Pathogens in Southeast Asian Frog Trade

Amphibian trade is known to facilitate the geographic spread of pathogens. Here we assess the health of amphibians traded in Southeast Asia for food or as pets, focusing on Batrachochytrium dendrobatidis (Bd), ranavirus and general clinical condition. Samples were collected from 2,389 individual animals at 51 sites in Lao PDR, Cambodia, Vietnam and Singapore for Bd screening, and 74 animals in Cambodia and Vietnam for ranavirus screening. Bd was found in one frog (n = 347) in Cambodia and 13 in Singapore (n = 419). No Bd was found in Lao PDR (n = 1,126) or Vietnam (n = 497), and no ranavirus was found in Cambodia (n = 70) or Vietnam (n = 4). Mild to severe dermatological lesions were observed in all East Asian bullfrogs Hoplobatrachus rugolosus (n = 497) sampled in farms in Vietnam. Histologic lesions consistent with sepsis were found within the lesions of three frogs and bacterial sepsis in two (n = 4); one had Gram-negative bacilli and one had acid-fast organisms consistent with mycobacterium sp. These results confirm that Bd is currently rare in amphibian trade in Southeast Asia. The presence of Mycobacterium-associated disease in farmed H. rugolosus is a cause for concern, as it may have public health implications and indicates the need for improved biosecurity in amphibian farming and trade.     

Subcutaneous fat remodelling in Southeast Asian infants and children

Longitudinal data on 1,048 Thai children were evaluated for evidence of subcutaneous fat remodelling. Fat distribution, as defined by 100 (triceps/[triceps + subscapular]), was more pronounced in the limbs during infancy but shifted toward the trunk thereafter. Subsequent stepwise regression analysis indicated that biological age--as measured by Gruelich-Pyle bone age--and weight together explained between 0.8% and 14.5% of variance in fat distribution, with generally larger R2 values over age and for males. Relationships were curvilinear, with sex differences in slope. Path analysis supported the model that weight was a major causal agent primarily after infancy, whereas biological age had a small influence both in infancy and in late childhood. These findings indicate that trunk fat deposition is a normal feature of childhood. They also suggest that hypotheses which associate elevated trunk fatness with disorders of glucose metabolism are invalid for younger children.     

Phylogeny and cryptic diversification in Southeast Asian flying geckos

The closed-canopy forests of Southeast Asia are home to an impressive number of vertebrates that have independently evolved morphologies that enhance directed aerial descent (gliding, parachuting). These assemblages include numerous mammal, frog, snake, and lizard clades. Several genera of gekkonid lizards, in particular, have evolved specialized structures such as cutaneous expansions, flaps, and midbody patagia, that enhance lift generation in the context of unique gliding and parachuting locomotion. The genus Ptychozoon represents arguably the most morphologically extreme, highly specialized clade of gliding geckos. Despite their notoriety and celebrated locomotor ability, members of the genus Ptychozoon have never been the subject of a species-level molecular phylogenetic analysis. In this paper, we utilize molecular sequence data from mitochondrial and nuclear gene fragments to estimate the evolutionary relationships of this unique group of flying geckos. Capitalizing on the recent availability of genetic samples for even the rarest of known species, we include the majority of known taxa and use model-based phylogenetic methods to reconstruct their evolutionary history. Because one species, P. kuhli, exhibits an unusually wide distribution coupled with an impressive range of morphological variation, we additionally use intensive phylogeographic/population genetic sampling, phylogenetic network analyses, and Bayesian species delimitation procedures to evaluate this taxon for the possible presence of cryptic evolutionary lineages. Our results suggest that P. kuhli may consist of between five and nine unrecognized, distinct species. Although we do not elevate these lineages to species status here, our findings suggest that lineage diversity in Ptychozoon is likely dramatically underestimated.     

Sexual dimorphism in Southeast Asian crania: A geometric morphometric approach

Despite a number of studies stating that sexual dimorphism is population specific, sexual differences in Southeast Asian populations have received little attention. Previous studies in this region have focused on samples from Thailand or East Asian populations from China and Japan, examining sexual dimorphism predominantly of the postcranial bones, teeth and mandible with comparatively few cranial studies. These earlier studies have used traditional methods to metrically assess differences between the sexes. The aim of this study is to use geometric morphometric methods for the first time to quantify sexual dimorphism of Southeast Asian crania and extend knowledge of cranial sexual dimorphism beyond China, Japan and Thailand. A total of 35 unilateral and midline landmark coordinates were collected from 144 mainland and island Southeast Asian crania (89 male, 55 female). Using the shape analysis software Morphologika, principal components analysis and thin plate splines allowed for the statistical and visual exploration of shape differences. Differences included relative facial breadth, particularly across the zygomatic and postorbital regions and cranial vault breadth. Significant size dimorphism was also apparent. Overall expected accuracies were highest in the discriminant analysis using both shape and centroid size (86.8%).     

The state and conservation of Southeast Asian biodiversity

Southeast Asia is a region of conservation concern due to heavy losses of its native habitats. In this overview, we highlight the conservation importance of Southeast Asia by comparing its degree of species endemism and endangerment, and its rate of deforestation with other tropical regions (i.e., Meso-America, South America, and Sub-Saharan Africa). Southeast Asia contains the highest mean proportion of country-endemic bird (9%) and mammal species (11%). This region also has the highest proportion of threatened vascular plant, reptile, bird, and mammal species. Furthermore, not only is Southeast Asia’s annual deforestation rate the highest in the tropics, but it has also increased between the periods 1990–2000 and 2000–2005. This could result in projected losses of 13–85% of biodiversity in the region by 2100. Secondary habitat restoration, at least in certain countries, would allow for some amelioration of biodiversity loss and thus potentially lower the currently predicted extinction rates. Nonetheless, urgent conservation actions are needed. Conservation initiatives should include public education, sustaining livelihoods, and ways to enhance the sustainability of agriculture and increase the capacity of conservation institutions. Furthermore, these actions should be country-specific and not ignore areas heavily populated by humans, as they can also harbour high numbers of threatened species. We urge that cooperative conservation initiatives be undertaken and support (e.g., capacity-building) be given by more developed countries in the region and beyond.     

The neolithic demographic transition and oral health: The Southeast Asian experience

The purpose of this article is to present new oral health data from Neolithic An Son, southern Vietnam, in the context of (1) a reassessment of published data on other Neolithic, Bronze, and Iron Age Southeast Asian dental series, and (2) predictions of the Neolithic Demographic Transition (NDT). To this end, frequencies for three oral conditions (caries, antemortem tooth loss, and alveolar lesions) were investigated for seven Southeast Asian adult dental series from Thailand and Vietnam with respect to time period, age‐at‐death and sex. A clear pattern of elevated rates for oral disease in the Neolithic followed by a marked improvement in oral health during the Bronze and Iron Ages was observed. Moreover, rates of caries and antemortem tooth loss for females were almost without exception higher than that for males in all samples. The consensus view among Southeast Asian bioarchaeologists that oral health did not decline with the adoption/intensification of agriculture in Southeast Asia, can no longer be supported. In light of evidence for (1) the low cariogenicity of rice; (2) the physiological predisposition of females (particularly when pregnant) to poorer oral health; and (3) health predictions of the NDT model with respect to elevated levels of fertility, the most plausible chief explanation for the observed patterns in oral health in Southeast Asia is increased levels of fertility during the Neolithic, followed by a decline in fertility during the subsequent Bronze and Iron Ages. Am J Phys Anthropol 152:197–208, 2013. © 2013 Wiley Periodicals, Inc.     

A survey of the mycorrhization of Southeast Asian ferns and lycophytes

The colonisation of land by plants may not have been possible without mycorrhizae, which supply the majority of land plants with nutrients, water and other benefits. In this sense, the mycorrhization of basal groups of land plants such as ferns and lycophytes is of particular interest, yet only about 9% of fern and lycophyte species have been sampled for their mycorrhization status, and no community‐level analyses exist for tropical fern communities. In the present study, we screened 170 specimens of ferns and lycophytes from Malaysia and Sulawesi (Indonesia), representing 126 species, and report the mycorrhization status for 109 species and 19 genera for the first time. Mycorrhizal colonisations were detected in 96 (56.5%) of the specimens, 85 of which corresponded to arbuscular mycorrhizae (AMF), three to dark‐septate endophytes (DSE) and four to mixed colonisations (AMF + DSE). DSE colonisations were lower than in comparable samples of ferns from the Andes, suggesting a geographical or taxonomic pattern in this type of colonisation. Epiphytes had significantly lower levels of colonisation (26.1%) than terrestrial plants (70.7%), probably due to the difficulty of establishment of mycorrhizal fungi in the canopy habitat.     

Inversion polymorphism in Southeast Asian populations of the Drosophila nasuta subgroup

Heterozygosity for chromosomal arrangements was investigated in four species of the nasuta complex. D. sulfurigaster albostrigata, D. albomicans and D. kohkoa are highly polymorphic whereas D. pulaua is monomorphic. Inversions were identified with the aid of photographic chromosome maps. The geographic distribution and frequencies of inversions detected and their possible phylogenies were discussed. Most inversions in D.s. albostrigata and D. albomicans occur on chromosome IIL. In D. kohkoa there is marked preponderance of inversions on chromosome III. Non-random association of certain inversions was noted. Variation in frequencies of inversions is interpreted as a result of adaptation to local ecogeographic conditions. Shared extant polymorphisms indicate phylogenetic relationships between species.The contents of this paper were incorporated in a Ph.D. thesis accepted by the University of Queensland in 1978. The author's present address is: Unit Genetik, Universiti Kebangsaan Malaysia, Jalan Pantai Baru, Kuala Lumpur, Malaysia.     

Isolation and characterization of microsatellites in the Southeast Asian river catfish Mystus nemurus

A total of 26 simple sequence repeats were identified using a random amplified polymorphic DNA (RAPD) based technique in the Southeast Asian river catfish Mystus nemurus. We report on the characterization of five polymorphic microsatellite loci in M. nemurus. The average number of alleles per locus was 3.2. These are the first microsatellite loci that have been developed for this species. These markers should prove useful as tools for managing the brood stocks and for future aquacultural development of this species.