GENETIC VARIATION OF DOMESTICATED DISCUS (Symphysodon spp.)

Tian T. Ng^1,2, Yeong Y. Sung¹, Muhd Danish-Daniel¹, Patrick Sorgeloos³, Yves V. de Peer^4,5, Li L. Wong¹, Min P. Tan^1*

¹Institute of Marine Biotechnology, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

²Aquacity Tropical Fish Sdn. Bhd., No.411, Jalan E2/7, Taman Ehsan, Kepong, 52100, Kuala Lumpur, Malaysia

³Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Ghent University, Ghent, B-9000, Belgium

⁴Center for Plant Systems Biology, VIB, Ghent, B-9052, Belgium

⁵Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, B-9052, Belgium.

*Corresponding author: mptan@umt.edu.my

Domesticated discus (Symphysodon spp.) exhibits highly diversified phenotypes appearances. However, genetic basis of the discus varieties and the relationship among them, that is fundamental and crucial for a proper management and breeding program, is currently unavailable. The present study focuses on the genetic relationship of the four wild types (Green, Heckel, Blue and Brown) and ten selected domesticated discus (Blue Diamond, Ghost, Golden, Snow White, Albino Red Cover, Red Snakeskin, Golden Tiger, Rose Red, Pigeon Blood and Leopard), inferred from the mitochondrial DNA cytochrome c oxidase subunit 1 and cytochrome b genes, and nuclear DNA recombination activating gene 1. Concatenated nucleotide sequences truncated to 3,242 base pair revealed that the Green discus was comparatively most differentiated (0.56–0.65%) from the other wild discus, while Blue, Brown and Heckel were closely related (0.03-0.22%). Specimens of the same group formed high bootstrap supported clusters (> 77%) and were clustered with own members in the gene tree except Red Snakeskin and Rose Red, indicating occurrence of phenotypic ambiguity leading to misclassification of discus in fish farm. Rose Red was mutated from Brown discus. Pigeon Blood formed a separate cluster in the gene tree and differed genetically the most from all the others, suggesting a possible historical crossbreeding attempt using genetically distant parents. Genetic homogeneity was observed among Blue Diamond, Ghost, Golden, Snow White, Albino Red Cover, Red Snakeskin and Leopard, with all these varieties linked closely to Heckel, Blue and Brown, indicating these are the likely genetic origin for these varieties. This finding also revealed discus flexibility in developing progeny with diverse physical appearances. High phenotypic variability in the absence of genetic variants may be associated with adaptive phenotypic plasticity in discus to better adapt in novel environments. The results presented herein suggest an inclusive fitness advantage for inbreeding individuals in discus, as part of the biparental care strategy in Cichlid fishes. Our study demonstrated that a genetic-based classification for selective breeding in tank-bred discus is optional, while a systematic classification using phenotypic features such as background colour, body markings and other traits for breeding management, instead is more relevant and economical for discus breeders/enthusiasts worldwide.

Keywords: discus Symphysodon, genetics, inbreeding, mitochondrial DNA, varieties.

PRELIMINARY ASSESSMENT OF CRASSOSTREA SP. GENETICS FROM NORTHERN PENINSULAR MALAYSIA

Syamim Balqis Shamsul Bahari ¹, Norainy Mohd Husin¹

¹Institute of Tropical Aquaculture and Fisheries (AKUATROP), Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia.

Corresponding author: norainyhusin@umt.edu.my

Crassostrea oyster is one of the well-known oyster in Malaysia. There are various kind of oysters that can be found in Malaysia and among them are Crassostrea iredalei, Crassostrea belcheri, Saccostrea echinata, Ostrea folium, and Hyotissa hyotis. The high demand of Crassostrea sp. for commercial purposes is the main reason for establishment of its aquaculture and this will reduce the threat to its natural populations. This study used the sample of Crassostrea sp. from Kelantan and Kedah, Malaysia. The objective of the study is to identify the exact Crassostrea species that can be found in Kelantan and Kedah by using mitochondrial cytochrome oxidase subunit I (COI) gene. The study also identifies and compare the population genetics of Crassostrea from the two locations. The BLAST results showed that the sample from Kelantan are Crassostrea iredalei and Crassostrea belcheri while from Kedah are Crassostrea iredalei and Crassostrea saidii. The results showed low to moderate nucleotide diversity π (0.0006-0.007) and moderate to high haplotype diversity ℎ (0.4-0.9). The phylogenetic neighbour-joining tree analysis shows better understanding between species and populations. The results of this study have significant potentials for Malaysia's aquaculture industry, population control and monitoring as well as wild oyster species protection in the future.

Keywords: Crassostrea sp., Population genetics, CO1, Phylogenetic tree, Aquaculture

REVEALING THE HIDDEN DIVERSITY OF MARINE BROWN ALGAL GENUS LOBOPHORA (DICTYOTACEAE) FROM THE GULF OF THAILAND

Anirut Klomjit^1,* and ‪Narongrit Muangmai¹

Department of Fishery Biology, Faculty of Fisheries, Kasetsart University,  Chatuchak, Bangkok 10900, Thailand

^*Corresponding author: anirut.klo@ku.th

Marine brown macroalgal genus Lobophora plays important ecological roles in many marine ecosystems. This group received much attention over the past decade, and a considerable number of new species were identified globally. However, our knowledge of the genus diversity and ecology along coasts of Thailand are still limited. This study investigated the diversity of Lobophora from Gulf of Thailand using morphological data together with DNA sequences from plastid (psbA) markers. A total of 62 Lobophora specimens was collected from 19 sites in both eastern and western Gulf of Thailand. Our combined morphological and genetic data revealed the occurrence of seven Lobophora species (L. abscondita, L. boussoleae, L. challengeriae, L. lamourouxii, L. obscura, L. pachyventera, and Lobophora sp. 115), two of which (L. abscondita, L. boussoleae, L. challengeriae, L. lamourouxii, and Lobophora sp. 115) were newly recorded in Thailand.  Lobophora abscondita, L. obscura and L. pachyventera occurred both on western and eastern coasts of the Gulf, whereas L. challengeriae and Lobophora sp. 115 were confined to the eastern side, and L. boussoleae and L. lamourouxii were restricted to the western side. Our finding highlights the surprisingly high diversity of Lobophora in the Gulf of Thailand, and provides useful knowledge to support ongoing and future research on coral–macroalgal ecological relationships.

Keywords: Distribution, Macroalgae, Phaeophyceae, Phylogeny, Taxonomy

MOLECULAR TAXONOMY OF FISH COMMUNITY IN A MANGROVE HOTSPOT OF SOUTHEAST ASIA

SitiAzizah Mohd. Nor1*, Danial Hariz Zainal Abidin 2, Sébastien Lavoué2, Masazurah A. Rahim4, Noorul Azliana Jamaludin5, Noor Adelyna Mohammed Akib2,3

1 Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Nerus 21030, Malaysia

2Centre for Global Sustainability Studies (CGSS), Universiti Sains Malaysia, Penang 11800, Malaysia

3School of Biological Sciences, Universiti Sains Malaysia, Penang, 11800, Malaysia

4Fisheries Research Institute, Batu Maung, Penang, 11960, Malaysia.

5Fisheries Research Institute, Perak, 32000, Malaysia.

*Corresponding author: s.azizah@umt.edu.my

The Merbok Estuary comprises one of the largest remaining mangrove forests in Peninsular Malaysia. Its value is signifcant as it provides important services to local and global communities. It also offers a unique opportunity to study the structure and functioning of mangrove ecosystems. However, its biodiversity is still partially inventoried, limiting its research value. A recent checklist based on morphological examination, reported 138 fsh  species residing or frequenting the Merbok Estuary. In this work, we reassessed the fish diversity of the Merbok Estuary by DNA barcoding 350 specimens assignable to 134 species initially identifed based on morphology. Our results consistently revealed the presence of 139 Molecular Operational Taxonomic Units (MOTUs). Of these, 123 are congruent with morphology-based species delimitation (one species=one MOTU). In two cases, two morphological species share the same MOTU (two species=one MOTU), while we unveiled cryptic diversity (i.e. COI-based genetic variability > 2%) within seven other species (one species = two MOTUs), calling for further taxonomic investigations. This study provides a comprehensive core-list of fsh taxa in Merbok Estuary, demonstrating the advantages of combining morphological and molecular evidence to describe diverse but still poorly studied tropical fsh communities. It also delivers a large DNA reference collection for brackish fshes occurring in this region which will facilitate further biodiversity-oriented research studies and management activities

Keywords: Mangrove Estuary, DNA barcoding, fish diversity, MOTU

MOLECULAR IDENTIFICATION OF KAPPAPHYCUS SPECIES COLLECTED IN ILOILO AND ROMBLON

John Rey T. Rasgo¹, Jonalyn P. Mateo^1,2*, Rema C. Sibonga^2,3, Victor Marco Emmanuel N. Feriols², Anicia Q. Hurtado², Maria Rovilla J. Luhan²

¹Institute of Marine Fisheries and Oceanology, University of the Philippines Visayas Miagao, Philippines 5023

²Institute of Aquaculture, University of the Philippines Visayas Miagao, Philippines 5023

³Center for Chemical Biology and Biotechnology, University of San Agustin, Iloilo City, 5000, Philippines

*Corresponding author: jpmateo@up.edu.ph

For more than 50 years, Kappaphycus, specifically K. alvarezii and K. striatus, have been cultured in the Philippines. Both species showed different varieties and color morphotypes which led to confusion, difficulties in species identification and eventually resulted to misidentification owing to its morphologically diverse nature, lack of clear diagnostic on morphological characteristics and inconsistent use of local and commercial names. The use of molecular markers has been proven to be effective in delineating Kappaphycus species from each other. In this study, cultivated seaweeds from Iloilo and Romblon were collected, morphologically described and analyzed for molecular identifiction. Genomic DNA was extracted using a modified CTAB protocol and amplified by polymerase chain reaction (PCR) using COI-5P and cox 2-3 spacer as molecular markers. The PCR products were purified and sent to Philippine Genome Center Visayas for sequencing. Based on external morphology, specimen from Iloilo and Romblon were initially identified as K. alvarezii (tambalang variety) and K. striatus (kulot variety), respectively. The species-level affiliation of the generated sequences was initially determined using BLAST analysis and confirmed by phylogenetic analysis. Both Iloilo and Romblon specimens were K. alvaezii based on BLAST results. The maximum likelihood tree revealed that the two specimens are of the same clade with other K. alvarezii specimens. In summary, kulot and tambalang, though morphologically different are both K. alvarezii. Thus, molecular technique is an important tool in proper identification of the cultivated seaweed.

Keywords: Color morphotypes, Kappaphcyus, Phylogenetic analysis