Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

. Astarini IA, Ningsih EY, Simanungkalit D, Ardiana SA, Al Malik MD, Yusmalinda NLA, Sembiring A, Pertiwi NPD, Cahyani NKD, Collins A. 2021. Genetic variation of longtail tuna Thunnus tonggol landed in four fish markets in Indonesia based on mitochondrial DNA. Biodiversitas 22: 1644-1651. Longtail tuna (Thunnus tonggol, Family: Scombridae) is an economically valuable neritic species found in tropical and subtropical waters in the Indo-Pacific region. High catch numbers, which have been decreasing, could negatively impact this tuna’s population level. Little research has been conducted on the longtail tuna population in Indonesia. This study aims to determine the genetic diversity and potential population structure of longtail tuna landed in four fish markets in Indonesia (representing three sampling locations because two markets are relatively close to each other) based on sequences of a region of mitochondrial control region (d-loop). A total of 101 samples, out of 110, were identified and confirmed as T. tonggol species by amplifying and sequencing a fragment of d-loop (amplicons ranging from 482 - 523 bp). Neighbor-joining analysis resulted in a topology with all samples grouped into one clade with an average genetic distance of 0.020. Meanwhile, haplotype diversity (Hd) and nucleotide diversity (?) values of the longtail tuna samples were 0.9939 and 0.0192, respectively. The fixation index (Fst) value was -0.00507, with p> 0.05, which indicates that there is no significant population structure among the longtail tuna collected from four fish markets representing three sampling locations. The results of this analysis can be used as basic data in planning sustainable fisheries management efforts.

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Genetic variation of longtail tuna Thunnus tonggol landed in four fish markets in Indonesia based on mitochondrial DNA

Benthic species, though ecologically important, are vulnerable to genetic loss and population size reduction due to impacts from fishing trawls. An assessment of genetic diversity and population structure is therefore needed to assist in a resource management program. To address this issue, the two-spined yellowtail stargazer (Uranoscopus cognatus) was collected within selected locations in the Indo-West Pacific (IWP). The partial mitochondrial DNA cytochrome c oxidase subunit 1 and the nuclear DNA recombination activating gene 1 were sequenced. Genetic diversity analyses revealed that the populations were moderately to highly diversified (haplotype diversity, H = 0.490-0.900, nucleotide diversity, π = 0.0010-0.0034) except sampling station (ST) 1 and 14. The low diversity level, however was apparent only in the matrilineal marker (H = 0.118-0.216; π = 0.0004-0.0008), possibly due to stochastic factors or anthropogenic stressors. Population structure analyses revealed a retention of ancestral polymorphism that was likely due to incomplete lineage sorting in U. cognatus, and prolonged vicariance by the Indo-Pacific Barrier has partitioned them into separate stock units. Population segregation was also shown by the phenotypic divergence in allopatric populations, regarding the premaxillary protrusion, which is possibly associated with the mechanism for upper jaw movement in biomechanical feeding approaches. The moderate genetic diversity estimated for each region, in addition to past population expansion events, indicated that U. cognatus within the IWP was still healthy and abundant (except in ST1 and 14), and two stock units were identified to be subjected to a specific resource management program.

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Genetic diversity, population structure and historical demography of the two-spined yellowtail stargazer (Uranoscopus cognatus).

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 FST,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 FSTpairwise 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.

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

This study aimed at assessing the genotype variation among six tuna fish collected from certain Libyan and Egyptian coastal regions and the molecular characterization due to the prevailing ecological parameters using SRAP and ISSRs. In addition, the current work addressed the impact of some ecological factors in water for tuna biodiversity analysis. ISSR analysis is useful for the assessment of genetic diversity among the genotypes of bluefin tuna. It is possible to conclude that, the short the distance between any two locations, the more they increase the similarity between the two genotypes collected total ratio polymorphism The lowest number of SRAP amplified fragments with primer pair ME9xEM9 where it three bands only. While the highest numbers of SRAP amplified fragments were with primer pair EM2xME5, where it showed 14 bands followed by primer pair ME5xEM3 produced total number of 13 bands, five fragments were unique bands in EM4xME4 and three bands in primer ME2xEM5. Primer pair ME7xEM7 one unique band also primer pair ME9xEM9 produced two unique bands. These results that SRAP-PCR analysis useful for genotypes and assessment of genetic diversity among the six genotypes of blue fin tuna. These results was agreed with the previous studies of as they showed the efficiency of molecular genotyping technique assessing genetic divergence in a marine fish with high dispersal potential. these results in agreement those results which obtained where they studied the genetic diversity of wild and natural populations of ( Megalobrama amblycephala ) fish using SRAP markers and assessed the genetic diversity among three natural populations. The pairwise comparison test shows a few genetic differentiations between blue-fin tuna populations. The distribution shows a relationship between different geographic locations. They stated that several approaches should be taken to support the life cycle of blue-fin tuna. The overall result shows that there has not been any change of genetic blue-fin

Eco-taxonomic study for some tuna genotypes collected from Egyptian and Libyan coasts on the molecular level

The population genetic diversity and demographic history of the longtail tuna Thunnus tonggol in Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals of T. tonggol were sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФST suggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989-1.000; ND5 = 0.848-0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019-0.025; ND5 = 0.0017-0.003), "star-like" haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations of T. tonggol in Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.

Noorhani Syahida Kasim

Papers

Recent population expansion of longtail tuna Thunnus tonggol (Bleeker, 1851) inferred from the mitochondrial DNA markers.