The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼ 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼ 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.
Despite is known to have widespread distribution and the most active species of the family Chlorocyphidae, the molecular data of Rhinocypha fenestrella (Rambur, 1842) are relatively scarce. The present study is the first that examined the genetic diversity and phylogeographic pattern of the peacock jewel-damselfly R. fenestrella by sequencing the cytochrome C oxidase I (cox1) and 16S rRNA gene regions from 147 individuals representing eight populations in Malaysia. A total of 26 and 10 unique haplotypes were revealed by the cox1 and 16S rRNA genes, respectively, and 32 haplotypes were recovered by the concatenated sequences of cox1+16S. Analyses indicated that haplotype AB2 was the most frequent and the most widespread haplotype in Malaysia while haplotype AB1 was suggested as the common ancestor haplotype of the R. fenestrella that may arose from the Negeri Sembilan as discovered from cox1+16S haplotype network analysis. Overall haplotype and nucleotide diversities of the concatenated sequences were Hd = 0.8937 and Pi = 0.0028, respectively, with great genetic differentiation (FST = 0.6387) and low gene flow (Nm = 0.14). Population from Pahang presented the highest genetic diversity (Hd = 0.8889, Pi = 0.0022, Nh = 9), whereas Kedah population demonstrated the lowest diversity (Hd = 0.2842, Pi = 0.0003, Nh = 4). The concatenated sequences of cox1+16S showed genetic divergence ranging from 0.09% to 0.97%, whereas the genetic divergence for cox1 and 16S rRNA genes were 0.16% to 1.63% and 0.01% to 0.75% respectively. This study provides for the first-time insights on the intraspecific genetic diversity, phylogeographic pattern and ancestral haplotype of Rhinocypha fenestrella. The understanding of molecular data especially phylogeographic pattern can enhance the knowledge about insect origin, their diversity, and capability to disperse in particular environments.
Haemonchus contortus is a highly pathogenic nematode parasite of sheep and goats. This work was conducted to investigate the population and host variations of the parasitic nematode H. contortus of sheep and goats from Malaysia and Yemen. Eight morphological characters were investigated, namely the total body length, cervical papillae, right spicule, left spicule, right barb, left barb, gubernaculum and cuticular ridge (synlophe) pattern. Statistical analysis showed the presence of morphological variation between populations of H. contortus from Malaysia and Yemen, with minor variation in the synlophe pattern of these isolates. Isolates from each country were grouped together in the scatterplots with no host isolation. Body, cervical papillae and spicule lengths were the most important characters that distinguished between populations of the two countries. This variation between Malaysia and Yemen may be attributed to geographical isolation and the possible presence of a different isolate of this worm in each country.
Human adenovirus type 8 (HAdV-8) is the most common causative agent of a highly contagious eye disease known as epidemic keratoconjunctivitis (EKC). HAdV-8 strains have been classified into genome types HAdV-8A to 8K and HAdV/D1 to D12 according to restriction endonuclease analysis. This review focuses on the significance of HAdV-8 as an agent of EKC. Molecular analysis of HAdV-8 genome types HAdV-53 and HAdV-54 was performed to reveal potential genetic variation in the hexon and fiber, which might affect the antigenicity and tropism of the virus, respectively. On the basis of the published data, three patterns of HAdV-8 genome type distribution were observed worldwide: (1) genome types restricted to a microenvironment, (2) genome types distributed within a country, and (3) globally dispersed genome types. Simplot and zPicture showed that the HAdV-8 genome types were nearly identical to each other. HAdV-54 is very close to the HAdV-8P, B and E genomes, except in the hexon. In a restriction map, HAdV-8P, B, and E share a very high percentage of restriction sites with each other. Hypervariable regions (HVRs) of the hexon were conserved and were 100% identical among the genome types. The fiber knob of HAdV-8P, A, E, J and HAdV-53 were 100% identical. In phylogeny, HVRs of the hexon and fiber knob of the HAdV-8 genome types segregated into monophyletic clusters. Neutralizing antibodies against one genome type will provide protection against other genome types, and the selection of future vaccine strains would be simple due to the stable HVRs. Molecular analysis of whole genomes, particularly of the capsid proteins of the remaining genome types, would be useful to substantiate our observations.
Although a previous study predicted that Japanese encephalitis virus (JEV) originated in the Malaysia/Indonesia region, the virus is known to circulate mainly on the Asian continent. However, there are no reported systematic studies that adequately define how JEV then dispersed throughout Asia.
Phylogenetic analysis was performed on hepatitis B virus (HBV) strains obtained from 86 hepatitis B surface antigen (HBsAg) positive donors from Thailand originating throughout the country. Based on the S gene, 87.5% of strains were of genotype C while 10.5% were of genotype B, with all genotype B strains obtained from patients originating from the central or the south Thailand. No genotype B strains were found in the north of Thailand. Surprisingly, one patient was infected with a genotype H strain while another patient was infected with a genotype G strain. Complete genome sequencing and recombination analysis identified the latter as being a genotype G and C2 recombinant with the breakpoint around nucleotide position 700. The origin of the genotype G fragment was not identifiable while the genotype C2 fragment most likely came from strains circulating in Laos or Malaysia. The performance of different HBsAg diagnostic kits and HBV nucleic acid amplification technology (NAT) was evaluated. The genotype H and G/C2 recombination did not interfere with HBV detection.
Zika virus (ZIKV) is a mosquito-borne flavivirus distributed throughout much of Africa and Asia. Infection with the virus may cause acute febrile illness that clinically resembles dengue fever. A recent study indicated the existence of three geographically distinct viral lineages; however this analysis utilized only a single viral gene. Although ZIKV has been known to circulate in both Africa and Asia since at least the 1950s, little is known about the genetic relationships between geographically distinct virus strains. Moreover, the geographic origin of the strains responsible for the epidemic that occurred on Yap Island, Federated States of Micronesia in 2007, and a 2010 pediatric case in Cambodia, has not been determined.
Rhinoviruses (RV) are a major cause of Severe Acute Respiratory Infection (SARI) in children, with high genotypic diversity in different regions. However, RV type diversity remains unknown in several regions of the world. In this study, the genetic variability of the frequently circulating RV types in Northern Tunisia was investigated, using phylogenetic and phylogeographic analyses with a specific focus on the most frequent RV types: RV-A101 and RV-C45. This study concerned 13 RV types frequently circulating in Northern Tunisia. They were obtained from respiratory samples collected in 271 pediatric SARI cases, between September 2015 and November 2017. A total of 37 RV VP4-VP2 sequences, selected among a total of 49 generated sequences, was compared to 359 sequences from different regions of the world. Evolutionary analysis of RV-A101 and RV-C45 showed high genetic relationship between different Tunisian strains and Malaysian strains. RV-A101 and C45 progenitor viruses' dates were estimated in 1981 and 1995, respectively. Since the early 2000s, the two types had a wide spread throughout the world. Phylogenetic analyses of other frequently circulating strains showed significant homology of Tunisian strains from the same epidemic period, in contrast with earlier strains. The genetic relatedness of RV-A101 and RV-C45 might result from an introduction of viruses from different clades followed by local dissemination rather than a local persistence of an endemic clades along seasons. International traffic may play a key role in the spread of RV-A101, RV-C45, and other RVs.
Tuberculosis (TB) still constitutes a major public health problem in Malaysia. The identification and genotyping based characterization of Mycobacterium tuberculosis complex (MTBC) isolates causing the disease is important to determine the effectiveness of the control and surveillance programs.
The discordant prevalence of Helicobacter pylori and its related diseases, for a long time, fostered certain enigmatic situations observed in the countries of the southern world. Variation in H. pylori infection rates and disease outcomes among different populations in multi-ethnic Malaysia provides a unique opportunity to understand dynamics of host-pathogen interaction and genome evolution. In this study, we extensively analyzed and compared genomes of 27 Malaysian H. pylori isolates and identified three major phylogeographic lineages: hspEastAsia, hpEurope and hpSouthIndia. The analysis of the virulence genes within the core genome, however, revealed a comparable pathogenic potential of the strains. In addition, we identified four genes limited to strains of East-Asian lineage. Our analyses identified a few strain-specific genes encoding restriction modification systems and outlined 311 core genes possibly under differential evolutionary constraints, among the strains representing different ethnic groups. The cagA and vacA genes also showed variations in accordance with the host genetic background of the strains. Moreover, restriction modification genes were found to be significantly enriched in East-Asian strains. An understanding of these variations in the genome content would provide significant insights into various adaptive and host modulation strategies harnessed by H. pylori to effectively persist in a host-specific manner.
Edentistoma octosulcatum Tömösváry, 1882, is a rare, superficially millipede-like centipede known only from Borneo and the Philippines. It is unique within the order Scolopendromorpha for its slow gait, robust tergites, and highly modified gizzard and mandible morphology. Not much is known about the biology of the species but it has been speculated to be arboreal with a possibly vegetarian diet. Until now its phylogenetic position within the subfamily Otostigminae has been based only on morphological characters, being variably ranked as a monotypic tribe (Arrhabdotini) or classified with the Southeast Asian genus Sterropristes Attems, 1934. The first molecular data for E. octosulcatum sourced from a newly collected specimen from Sarawak were analysed with and without morphology. Parsimony analysis of 122 morphological characters together with two nuclear and two mitochondrial loci resolves Edentistoma as sister group to three Indo-Australian species of Rhysida, this clade in turn grouping with Ethmostigmus, whereas maximum likelihood and parsimony analyses of the molecular data on their own ally Edentistoma with species of Otostigmus. A position of Edentistoma within Otostigmini (rather than being its sister group as predicted by the Arrhabdotini hypothesis) is consistently retrieved under different analytical conditions, but support values within the subfamily remain low for most nodes. The species exhibits strong pushing behaviour, suggestive of burrowing habits. Evidence against a suggested vegetarian diet is provided by observation of E. octosulcatum feeding on millipedes in the genus Trachelomegalus.
This study provides a first description of the phylogeographic patterns and evolutionary history of two species of the mudskipper genus Periophthalmus. These amphibious gobies are distributed throughout the whole Indo-Pacific region and Atlantic coast of Africa, in peritidal habitats of soft-bottom coastal ecosystems. Three sequence datasets of two widely distributed species, Periophthalmus argentilineatus and P. kalolo, were obtained by amplifying and sequencing two mtDNA markers (D-loop and 16S rDNA) and the nDNA rag1 region. The three datasets were then used to perform phylogeographic, demographic and population genetic analyses. Our results indicate that tectonic events and past climatic oscillations strongly contributed to shape present genetic differentiation, phylogeographic and demographic patterns. We found support for the monophyly of P. kalolo, and only shallow genetic differentiation between East-African and Indo-Malayan populations of this species. However, our collections of the morphospecies P. argentilineatus include three molecularly distinct lineages, one of them more closely related to P. kalolo. The presence of Miocenic timings for the most recent common ancestors of some of these morphologically similar clades, suggests the presence of strong stabilising selection in mudskippers' habitats. At population level, demographic analyses and palaeoecological records of mangrove ecosystems suggest that Pleistocene bottlenecks and expansion plus secondary contact events of the studied species were associated with recurrent sea transgressions during interglacials, and sea regressions or stable regimes during glacials, respectively.
A primary factor in population management and wildlife conservation is the delineation of population units derived from descriptions of population genetic structure. Yet, predicting factors that influence the patterns of gene flow in a population particularly at landscape scales remains a major challenge in evolutionary biology. Here we report a population genetic study of the mud crab Scylla olivacea examined based on a 542 bp segment of the mitochondrial DNA cytochrome c oxidase I gene among 91 individuals from six localities in the west and east coast of Peninsular Malaysia. In total 55 unique haplotypes were distinguished with 45 private haplotypes and a single common haplotype shared among all populations studied. The other ten haplotypes were shared among various populations. The sharing of this haplotype reflects the connection of the mangrove areas between east and west coast of Peninsular Malaysia. High haplotype diversity (h = 0.968 ± 0.021; mean ± SD) and low nucleotide diversity (π = 0.120 ± 0.015; mean ± SD) were displayed, which may be indicative of genetic bottleneck events. No significant phylogenetic lineages were recognized using neighbour-joining and maximum parsimony methods. Hierarchical AMOVA analysis indicated that 99.33 % of the genetic variation was contained within populations and 0.67 % occurred among populations, suggesting no geographical patterning among populations studied, supported by F st test. Mismatch distribution analysis showed that the observed distribution of the pairwise mutation differences among haplotypes was multimodal, which is not concordant with a sudden range expansion scenario. However, neutrality tests showed non-significant negative values suggesting that the populations studied may have experienced past population growth, but the expansion may have been restricted to separate local areas that resulted in the non-significant negative Fu's Fs and Tajima's D value. Overall, this present preliminary study was able to be a reference on the phylogenetic relationships and assessment of genetic structure of Scylla sp. in Malaysia.
To determine the geographic origin of the black fly Simulium suzukii on Okinawa Island, Japan, macrogenomic profiles derived from its polytene chromosomes were compared with those of mainland and other insular populations of S. suzukii and of the isomorphic Simulium tani species complex. The Okinawan population is a chromosomally unique cytoform, designated 'D,' which is essentially monomorphic and differs by about 27 fixed rearrangements from the chromosomal standard sequence for the subgenus Simulium and by two fixed differences from its nearest known relative, representing the type of S. suzukii, on the main islands of Japan. Chromosomal band sequences revealed two additional, sympatric cytoforms of S. suzukii, designated 'A' and 'B,' each with species status, in Korea, and a third cytoform, designated 'C,' on Hokkaido, Japan. A new cytoform, 'K,' of S. tani from Malaysia, representing the type of S. tani, is more closely related to cytoforms in Thailand, as are populations from Taiwan previously treated as S. suzukii but more closely aligned with S. tani and newly recognized as cytoform 'L' of the latter nominal species. Rooting of chromosomal band sequences by outgroup comparisons allowed directionality of chromosomal rearrangements to be established, enabling phylogenetic inference of cytoforms. Of 41 macrogenomic rearrangements discovered in the five new cytoforms, four provide evidence for a stepwise origin of the Okinawan population from populations characteristic of the main islands of Japan. The macrogenomic approach applied to black flies on Okinawa Island illustrates its potential utility in defining source areas for other species of flies including those that might pose medical and veterinary risks.
Malaysia remains as a crossroad of different cultures and peoples, and it has long been recognized that studying its population history can provide crucial insight into the prehistory of Southeast Asia as a whole. The earliest inhabitants were the Orang Asli in Peninsular Malaysia and the indigenous groups in Sabah and Sarawak. Although they were the earliest migrants in this region, these tribes are divided geographically by the South China Sea. We analyzed DNA sequences of 18 Orang Asli using mitochondrial DNA extracted from blood samples, each representing one sub-tribe, and from five Sarawakian Iban. Mitochondrial DNA was extracted from hair samples in order to examine relationships with the main ethnic groups in Malaysia. The D-loop region and cytochrome b genes were used as the candidate loci. Phylogenetic relationships were investigated using maximum parsimony and neighbor joining algorithms, and each tree was subjected to bootstrap analysis with 1000 replicates. Analyses of the HVS I region showed that the Iban are not a distinct group from the Orang Asli; they form a sub-clade within the Orang Asli. Based on the cytochrome b gene, the Iban clustered with the Orang Asli in the same clade. We found evidence for considerable gene flow between Orang Asli and Iban. We concluded that the Orang Asli, Iban and the main ethnic groups of Malaysia are probably derived from a common ancestor. This is in agreement with a single-route migration theory, but it does not dismiss a two-route migration theory.
Monstrilloid copepods are protelean parasites of different groups of marine benthic invertebrates. Only their first naupliar, preadult, and adult phases are planktonic. Monstrilloids are currently represented by more than 115 nominal species contained in four genera. Its taxonomic knowledge has been hampered by nomenclatural and descriptive problems derived from their peculiar ontogeny and poor definitions of taxa. One of the most important difficulties is that of matching males to females. The only reliable methods to link the sexes of a species are the confirmation of particular apomorphies shared by both sexes, finding both sexes in the same host or as a pre-copulatory male-female pair in the plankton, or by the use of molecular markers. A general overview of the morphology of the group and its life cycle is provided herein. Recently, upgraded descriptive standards have been established and the relevance of redescribing taxa based on type and museum specimens has been demonstrated. The rate of species description per decade has had several peaks between 1840 and 2010: (1971-1980, 1991-2000, 2001-2010), each related to the activity of a few researchers. An analysis of the world distribution of published records of the Monstrilloida revealed that the Northeast Atlantic is the best studied region (45% of all records), followed by the Northwestern Atlantic (17%); the least surveyed areas include regions of the southern hemisphere (less than 3%). The Northeast Atlantic region harbors the highest number of known species (32 nominal species), followed by the Caribbean Sea/Gulf of Mexico (24), the Mediterranean/Black Sea (19), Indonesia-Malaysia-Philippines region (17), Japanese waters (17), and the Brazil-Argentina area (16). Other than these generalized patterns, little can be concluded concerning the biogeography of the group. Many species records are doubtful or improbable, and purportedly cosmopolitan nominal species are being revealed as species complexes yet to be studied.
Sundaland has a dynamic geographic history because its landmasses were periodically interconnected when sea levels fell during glacial periods. Superimposed on this geographic dynamism were environmental changes related to climatic oscillations. To investigate how tropical taxa responded to such changes, we studied the divergence and demographic history of two co-distributed rainforest passerine species, Arachnothera longirostra and Malacocincla malaccensis. We sampled birds primarily from Borneo and the Malay Peninsula, which straddle the now-submerged Sunda shelf, and analysed multilocus DNA data with a variety of coalescent and gene genealogy methods. Cross-shelf divergence in both species occurred well before the last glacial maximum, i.e., before the most recent land connection. However, post-divergence gene flow occurred, and it was more pronounced in A. longirostra (a highly vagile nectarivore/insectivore) than in M. malaccensis (an understory insectivore). Despite current habitat continuity on Borneo, the population of M. malaccensis in northeastern Borneo is substantially divergent from that on the rest of the island. The NE population experienced dramatic demographic fluctuations, probably because of competition with the other population, which expanded from western Borneo after the mid-Pleistocene. In contrast, the Borneo population of A. longirostra has little structure and appears to have experienced demographic expansion 16 kya, long after it had diverged from the Malay Peninsula population (630-690 kya). Malay Peninsula populations of both species have remained relatively stable. Overall, the most recent glacial period was not the chief determinant of the evolutionary dynamics of our study species, and in this respect, they are different from temperate species.
One hundred isolates of Phytophthora infestans collected from 10 provinces in China between 1998 and 2004 were analyzed for mating type, metalaxyl resistance, mitochondrial DNA (mtDNA) haplotype, allozyme genotype, and restriction fragment length polymorphism (RFLP) with the RG-57 probe. In addition, herbarium samples collected in China, Russia, Australia, and other Asian countries were also typed for mtDNA haplotype. The Ia haplotype was found during the first outbreaks of the disease in China (1938 and 1940), Japan (1901, 1930, and 1931), India (1913), Peninsular Malaysia (1950), Nepal (1954), The Philippines (1910), Australia (1917), Russia (1917), and Latvia (1935). In contrast, the Ib haplotype was found after 1950 in China on both potato and tomato (1952, 1954, 1956, and 1982) and in India (1968 and 1974). Another migration of a genotype found in Siberia called SIB-1 (Glucose-6-phosphate isomerase [Gpi] 100/100, Peptidase [Pep] 100/100, IIa mtDNA haplotype) was identified using RFLP fingerprints among 72% of the isolates and was widely distributed in the north and south of China and has also been reported in Japan. A new genotype named CN-11 (Gpi 100/111, Pep 100/100, IIb mtDNA haplotype), found only in the south of China, and two additional genotypes (Gpi 100/100, Pep 100/100, Ia mtDNA haplotype) named CN-9 and CN-10 were identified. There were more diverse genotypes among isolates from Yunnan province than elsewhere. The SIB-1 (IIa) genotype is identical to those from Siberia, suggesting later migration of this genotype from either Russia or Japan into China. The widespread predominance of SIB-1 suggests that this genotype has enhanced fitness compared with other genotypes found. Movement of the pathogen into China via infected seed from several sources most likely accounts for the distribution of pathogen genotypes observed. MtDNA haplotype evidence and RFLP data suggest multiple migrations of the pathogen into China after the initial introduction of the Ia haplotype in the 1930s.
A phylogeographic study of an economically important freshwater fish, the striped snakehead, Channa striata in Sundaland was carried out using data from mtDNA ND5 gene target to elucidate genetic patterning. Templates obtained from a total of 280 individuals representing 24 sampling sites revealed 27 putative haplotypes. Three distinct genetic lineages were apparent; 1)northwest Peninsular Malaysia, 2)southern Peninsular, east Peninsular, Sumatra and SW (western Sarawak) and 3) central west Peninsular and Malaysian Borneo (except SW). Genetic structuring between lineages showed a significant signature of natural geographical barriers that have been acting as effective dividers between these populations. However, genetic propinquity between the SW and southern Peninsular and east Peninsular Malaysia populations was taken as evidence of ancient river connectivity between these regions during the Pleistocene epoch. Alternatively, close genetic relationship between central west Peninsular Malaysia and Malaysian Borneo populations implied anthropogenic activities. Further, haplotype sharing between the east Peninsular Malaysia and Sumatra populations revealed extraordinary migration ability of C. striata (>500 km) through ancient connectivity. These results provide interesting insights into the historical and contemporary landscape arrangement in shaping genetic patterns of freshwater species in Sundaland.
Giardia duodenalis is a protozoan parasite that can cause significant diarrhoeal diseases. Knowledge of population genetics is a prerequisite for ascertaining the invasion patterns of this parasite. In order to infer evolutionary patterns that could not be uncovered based on the morphological features, a population genetic study with the incorporation of molecular marker was carried out to access the genetic structure of G. duodenalis isolated from the Malaysian population and the global populations.