Contrasting genetic and morphological differentiation among geographical lineages of a stenotopic miniature rasborine, Boraras maculatus, in Peninsular Malaysia.

The variability in the stenotopic miniature rasborine Boraras maculatus (Cypriniformes: Danionidae: Rasborinae) across acidic-water habitats of Peninsular Malaysia (PM) was investigated using two molecular markers (the mitochondrial cytochrome c oxidase subunit I [COI] gene and the nuclear rhodopsin gene), as well as morphological evidence. Molecular phylogenetic analyses revealed differentiation among populations of B. maculatus in PM with the distinction of four allopatric lineages. Each of them was recognized as a putative species by automatic species delimitation methods. These lineages diverged from each other between 7.4 and 1.9 million years ago. A principal component analysis (PCA) was conducted to examine the multivariate variation in 11 morphometric measurements among three of these lineages. PCA results showed a significant overlap in morphological characteristics among these lineages. Additionally, a photograph-based machine learning approach failed to fully differentiate these lineages, suggesting limited morphological differentiation. B. maculatus represents a case of morphological stasis in a stenotopic miniature species. Strong habitat preference, coupled with long-term habitat fragmentation, may explain why each lineage of B. maculatus has a restricted distribution and did not disperse to other regions within and outside of PM, despite ample possibilities when the Sunda shelf was emerged and drained by large paleodrainages for most of the past 7 million years. The conservation status of B. maculatus and its peat swamp habitats are discussed, and it is concluded that peat swamps comprise several evolutionary units. Each of these units is considered a conservation unit and deserves appropriate protection.

Genetic Polymorphism and Phylogenetics of Aedes aegypti from Sudan Based on ND4 Mitochondrial Gene Variations.

This study investigated the genetic differences between Aedes aegypti subspecies (Aedes aegypti aegypti (Aaa) and Aedes aegypti formosus (Aaf)) from Sudan using the NADH dehydrogenase subunit 4 (ND4) mitochondrial gene marker. Nineteen distinct haplotypes of the ND4 were identified in female Aedes aegypti mosquitoes from the study sites. The phylogenetic relationship of the 19 ND4 haplotypes was demonstrated in a median-joining haplotype network tree with Aaa and Aaf populations found to share three haplotypes. The genetic variance (Pairwise FST values) was estimated and found to range from 0.000 to 0.811. Isolation by distance test revealed that geographical distance was correlated to genetic variation (coefficient value (r) = 0.43). The Polar maximum likelihood tree showed the phylogenetic relationship of 91 female Aaa and Aaf from the study sites, with most of the Aaf haplotypes clustered in one group while most of the Aaa haplotypes gathered in another group, but there was an admixture of the subspecies in both clusters, especially the Aaa cluster. The Spatial Analysis of Molecular Variance (SAMOVA) test revealed that the eight populations clustered into two phylogeographic groups/clusters of the two subspecies populations. The 2 Aedes aegypti subspecies seemed not to be totally separated geographically with gene flow among the populations.

Low morphological and genetic variation within the glass-perchlet Parambassis siamensis (Teleostei: Ambassidae) in Peninsular Malaysia.

We compare several populations of the glass-perchlet Parambassis siamensis (Fowler 1937) (Teleostei: Ambassidae) sampled throughout Peninsular Malaysia to determine their degree of differentiation, using both morphological and molecular characters. Our morphological analyses do not show evidence for the presence of more than one species, with the range of morphometric and meristic characters overlapping among populations. Our genetic analysis using partial sequences of the mitochondrial gene coding for the protein cytochrome c oxidase I (COI) reveals the existence of two clades that diverge from each other by a minimum uncorrected p-distance of 2.2%. The first clade comprises of specimens from south-eastern Peninsular Malaysia (Pahang and Endau-Rompin River basins) along with those from Cambodia (lower Mekong River). The second clade comprises of specimens from western Peninsular Malaysia (Selangor, Kurau, Perak, Muda and Kerian River basins) and north-eastern Peninsular Malaysia (Terengganu River basin), along with those from Chao Phraya River basin nearby Bangkok (type locality of P. siamensis). The presence of specimens with numerous melanophores on body sides in each of these two clades indicates that body marking pattern is not a valuable taxonomic character. This finding supports the conclusion that Chanda punctulata Fraser-Brunner 1955 is a junior synonym of P. siamensis. Altogether, our results support the hypothesis that all populations of P. siamensis in Peninsular Malaysia (along those from Chao Phraya and lower Mekong basins) are conspecific, comprising two genetically distinct, although close lineages. We further discuss the phenotypic plasticity within P. siamensis in relation to lotic and lentic habitats. Finally, we briefly discuss some implications for biogeography and possible causes explaining the distribution pattern.

Mitochondrial marker implies fishery separate management units for spotted sardinella, Amblygaster sirm (Walbaum, 1792) populations in the South China Sea and the Andaman Sea.

The spotted sardinella, Amblygaster sirm (Walbaum, 1792), is a commercial sardine commonly caught in Malaysia. Lack of management of these marine species in Malaysian waters could lead to overfishing and potentially declining fish stock populations. Therefore, sustainable management of this species is of paramount importance to ensure its longevity. As such, molecular information is vital in determining the A. sirm population structure and management strategy. In the present study, mitochondrial DNA Cytochrome b was sequenced from 10 A. sirm populations: the Andaman Sea (AS) (two), South China Sea (SCS) (six), Sulu Sea (SS) (one), and Celebes Sea (CS) (one). Accordingly, the intra-population haplotype diversity (Hd) was high (0.91-1.00), and nucleotide diversity (π) was low (0.002-0.009), which suggests a population bottleneck followed by rapid population growth. Based on the phylogenetic trees, minimum spanning network (MSN), population pairwise comparison, and F ST,and supported by analysis of molecular variance (AMOVA) and spatial analysis of molecular variance (SAMOVA) tests, distinct genetic structures were observed (7.2% to 7.6% genetic divergence) between populations in the SCS and its neighboring waters, versus those in the AS. Furthermore, the results defined A. sirm stock boundaries and evolutionary between the west and east coast (which shares the same waters as western Borneo) of Peninsular Malaysia. In addition, genetic homogeneity was revealed throughout the SCS, SS, and CS based on the non-significant F STpairwise comparisons. Based on the molecular evidence, separate management strategies may be required for A. sirm of the AS and the SCS, including its neighboring waters.

Distribution and Genetic Diversity of Aedes aegypti Subspecies across the Sahelian Belt in Sudan.

Aedes aegypti is the most important arboviral disease vector worldwide. In Africa, it exists as two morphologically distinct forms, often referred to as subspecies, Aaa and Aaf. There is a dearth of information on the distribution and genetic diversity of these two forms in Sudan and other African Sahelian region countries. This study aimed to explore the distribution and genetic diversity of Aedes aegypti subspecies using morphology and Cytochrome oxidase-1 mitochondrial marker in a large Sahelian zone in Sudan. An extensive cross-sectional survey of Aedes aegypti in Sudan was performed. Samples collected from eight locations were morphologically identified, subjected to DNA extraction, amplification, sequencing, and analyses. We classified four populations as Aaa and the other four as Aaf. Out of 140 sequence samples, forty-six distinct haplotypes were characterized. The haplotype and nucleotide diversity of the collected samples were 0.377-0.947 and 0.002-0.01, respectively. Isolation by distance was significantly evident (r = 0.586, p = 0.005). The SAMOVA test indicated that all Aaf populations are structured in one group, while the Aaa clustered into two groups. AMOVA showed 53.53% genetic differences within populations and 39.22% among groups. Phylogenetic relationships indicated two clusters in which the two subspecies were structured. Thus, the haplotype network consisted of three clusters.

DNA barcoding of shrimps from a mangrove biodiversity hotspot.

A total of 74 shrimp specimens were sequenced at a 584 bp segment of the cytochrome oxidase subunit I (COI) gene to examine patterns of DNA barcode variation in a mangrove biodiversity hotspot. The Maximum Likelihood tree, barcode gap analysis, Automatic Barcode Gap Discovery analysis and sequence comparisons with data available from Barcode of Life Data System and GenBank recovered 18 taxa of which 15 were identified to species level, 2 at genus level and a single taxon at order level. Two deep mitochondrial DNA lineage divergences were found in the giant tiger prawn, Penaeus monodon. It is suggested that one of the lineages is a consequence of an introduction from aquaculture activity. These results have provided a reliable barcode library for cataloguing shrimps in this area.

Genetic structure of the snakehead murrel, Channa striata (channidae) based on the cytochrome c oxidase subunit I gene: Influence of historical and geomorphological factors.

Nucleotide sequences of a partial cytochrome c oxidase subunit I gene were used to assess the manner in which historical processes and geomorphological effects may have influenced genetic structuring and phylogeographic patterns in Channa striata. Assaying was based on individuals from twelve populations in four river systems, which were separated into two regions, the eastern and western, of the biodiversely rich state of Perak in central Peninsular Malaysia. In 238 specimens, a total of 368-bp sequences with ten polymorphic sites and eleven unique haplotypes were detected. Data on all the twelve populations revealed incomplete divergence due to past historical coalescence and the short period of separation. Nevertheless, SAMOVA and F(ST) revealed geographical structuring existed to a certain extent in both regions. For the eastern region, the data also showed that the upstream populations were genetically significantly different compared to the mid- and downstream ones. It is inferred that physical barriers and historical processes played a dominant role in structuring the genetic dispersal of the species. A further inference is that the Grik, Tanjung Rambutan and Sungkai are potential candidates for conservation and aquaculture programmes since they contained most of the total diversity in this area.