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Genetic Differentiation and Population Structure of the Freshwater Snail Rivomarginella morrisoni (Gastropoda: Marginellidae) in Central and Southern Thailand
(2026-03-01)
Subpayakom, Navapong
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Wanitjirattikal, Puntipa
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Dumrongrojwattana, Pongrat
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Poeaim, Supattra
Rivomarginella morrisoni (Gastropoda: Marginellidae) is a narrowly distributed freshwater snail inhabiting drainage basins of central and southern Thailand. To clarify patterns of genetic differentiation across its range, 45 individuals from 11 sites across eight river basins were analyzed using two dominant molecular markers: sequence-related amplified polymorphism (SRAP) and inter-simple sequence repeats (ISSR). SRAP primers produced higher polymorphic information content (PIC) values than ISSR primers (0.35 vs. 0.27). Analysis of molecular variance (AMOVA) revealed strong population structure, with 80.29% of the genetic variation occurring among populations and 19.71% within populations Population differentiation statistic (PhiPT) = 0.803, p < 0.001). Unweighted Pair Group Method with Arithmetic mean (UPGMA) and principal coordinate analysis (PCoA) consistently separated central and southern populations, and STRUCTURE supported K = 2 as the most likely number of clusters. Similarly, principal component analysis (PCA) of morphological traits also distinguished specimens into two groups corresponding to these geographic regions, confirming region-specific divergence. Overall, the genetic and morphological patterns indicate restricted gene flow among basins and a clear separation between central and southern lineages of R. morrisoni. This study provides the first molecular evidence of population structure in this species and offers important baseline information for future taxonomic, ecological, and conservation research on freshwater marginellid snails.
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Saving the Mahachai Betta: Genetic Erosion and Conservation Priorities Under Urbanization Pressure
(2025-10-01)
Nguyen, Ton Huu Duc
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Budi, Trifan
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Pongsanarm, Tavun
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Panthum, Thitipong
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Singchat, Worapong
Background/Objectives: Mahachai Betta (Betta mahachaiensis) is a bubble-nesting fighting fish endemic to brackish habitats in Bangkok, Samut Sakhon, and Samut Prakan, where rapid urbanization and industrial growth threaten persistence. We evaluated genetic structure and diversity across 10 populations (81 individuals) to inform conservation planning. Methods: This study combined microsatellite genotyping (13 loci) with ecological niche modeling to assess genetic variability, population connectivity, and landscape–environmental drivers of differentiation. Results: Habitat loss and fragmentation were associated with reduced gene flow and decreased genetic diversity. Mean allelic richness was 2.65 and expected heterozygosity ranged from 0.20 to 0.46, with F<inf>ST</inf> values up to 0.400. Forward simulations predicted severe erosion of diversity within the next 12.5–37.5 years. Populations showed clear genetic subdivision, most pronounced in Samut Prakan and Samut Sakhon, with two Samut Sakhon populations (SKN3 and SKN7) reflecting strong environmental heterogeneity. Conclusions: Improving habitat connectivity and intensifying local community engagement are priority actions to enhance the resilience and long-term persistence of Mahachai Betta. This study provides the first integrated genetic and landscape-based assessment of the species, highlighting its rapid genetic erosion under urbanization and offering a foundation for targeted, evidence-based conservation strategies.
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Genetic Diversity and Selection of MHC I-UAA in Clariid Catfish from Thailand: Implications for Breeding and Conservation
(2025-09-01)
Nguyen, Ton Huu Duc
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Chalermwong, Piangjai
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Patta, Chananya
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Jaito, Wattanawan
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Singchat, Worapong
Background/Objectives: Understanding variabilities in the Major Histocompatibility Complex class I (MHC I) gene is essential for evaluating immunogenetic diversity in clariid catfish. MHC I plays a critical role in immune defense by presenting endogenous antigens to cytotoxic T cells. Therefore, we aimed to investigate the genetic diversity, selection patterns, and phylogenetic relationships of MHC I alleles in three important clariid catfish species (Clarias gariepinus, Clarias macrocephalus, and Clarias batrachus) across wild and hatchery populations in Thailand. Methods: Targeted next-generation sequencing of a 174 bp fragment partial exon 6 of MHC I-UAA gene was performed, along with phylogenetic analyses, neutrality tests and dN/dS analyses. Results: Overall, 91 novel alleles were identified in 674 individuals, all of which were novel (100% novelty), with none matching existing reference sequences, thereby revealing extensive variation in population-specific variants. Phylogenetic analyses revealed allele sharing among species, which was consistent with balanced selection. Neutrality tests and dN/dS analyses provided evidence of both purifying and diversifying selection, with episodic positive selection detected at multiple codon sites associated with the antigen-binding α1 domain. Distinct selection patterns among populations, influenced by local environmental conditions and human pressures, along with high allele richness, are reflected in the diversity of immunogenetic variations. Conclusions: These findings provide critical insights into immune adaptation and highlight the potential of MHC I as a functional marker for genetic monitoring. Although a causal relationship between MHC I polymorphism and disease resistance is debated, studies suggest associations with pathogen survival, indicating future implications for aquaculture breeding and conservation, particularly in marker-assisted selection for broodstock management in Thailand.
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Yield Response of Sweet Potato (Ipomoea batatas L.) Genotypes Cultivated in Post-Rice Paddy Field
(2025-01-01)
Ruttanaprasert, Ruttanachira
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Pinta, Wanwipa
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Pitak, Lakkana
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Janket, Anon
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Bunphan, Darika
Sweet potatoes (Ipomoea batatas L.) are a nutrient-rich root crop with substantial nutritional, economic, and environmental benefits. This study assessed nine sweet potato genotypes across three distinct locations in Thailand to evaluate yield potential, adaptability, and environmental influences. Trials used a randomized complete block design with four replications. Location 1 (Thatum District) featured sandy soil with moderate pH, high salinity, and balanced nutrients but lower phosphorus (P) and nitrogen (N). Location 2 (Maung District) had sandy, acidic soil but was the most chemically fertile, with high P and potassium (K). Location 3 (Rajamangala University of Technology Isan, Surin Campus) had loamy sand with higher silt content, acidic pH, low P, K, and electrical conductivity (EC). Results highlighted significant yield differences influenced by soil and environmental variability. Genotype SR18003 achieved the highest yield and harvest index, demonstrating strong adaptability and commercial potential. Strong correlations between storage root traits (number, size, and weight) indicate their usefulness for selection. The study underscores the importance of tailored soil management and location-specific genotypes in optimizing sweet potato production, contributing to resilient varieties, sustainable farming, and improved food security. Further research on genetics and agronomy can enhance breeding and cultivation systems.
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Growth performance and starch yield potential of arrowroot (Maranta arundinacea) from various locations in Thailand
(2024-01-01)
Ieamkheng, Supaporn
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Santibenchakul, Somtop
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Poonpaerdchon, Supattra
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Soem, Bunny
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Sooksawat, Najjapak
Ieamkheng S, Santibenchakul S, Poonpaerdchon S, Soem B, Sooksawat N. 2024. Growth performance and starch yield potential of arrowroot (Maranta arundinacea) from various locations in Thailand. Biodiversitas 25: 3750-3757. Arrowroot (Maranta arundinacea L.) is a tuberous type of medicinal that has high starch quality and good health benefits. This research studied the yield and growth characteristics of arrowroot samples from different 5 accessions in Thailand, along with their important properties for commercial use. Samples were collected from 5 field crops in Thailand: Tha Maka District, Kanchanaburi Province (Th-T-K); Sai Yok District, Kanchanaburi Province (Th-Sy-K); Ratchaburi Province (Th-RB); Chanthaburi Province (Th-Chan), and Sa Kaeo Province (Th-SK). The growth rate and yield of Thai arrowroot at 3, 6, and 9 months after planting were evaluated and the starch was extracted and characterized. During 3 months, there was only growth with no tuber yield; at 6 months, the arrowroot from Th-Sy-K had the highest growth rate and yield. The highest yields were at 9 months after planting, with the tuber weight per clump in the range of 596-2,980 g that produced 121.8-150.8 g of starch (8-10% yield). DNA fingerprinting analysis and the molecular study indicated no variation among the 5 accessions of arrowroot, indicating the uniformity and reliability of the samples. The results of the nutritional composition, the amounts of carbohydrates and amylose in the Th-Sy-K and Th-RB samples tended to increase with plant growth. At the same time, other contents, namely moisture, and lipid, decreased. The main component of the arrowroot starch was carbohydrate (87-91%), and the 9-month starch had high viscosity and heat-resistant values. In conclusion, arrowroot starch showed potential as a novel raw material for application in the food industry and possibly in cosmetic and pharmaceutical manufacturing.

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