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Background: Perna viridis (Linnaeus, 1758), the Asian green mussel, is native to the Asia-Pacific region. The species is extensively distributed in the Indian subcontinent and is a candidate species for aquaculture in the Southeast Asian region. Availability of genetic information on wild populations is essential for the effective conservation and management of Perna species. The present study assessed the genetic variation and population structure across the distribution range of this species from the Indian peninsula by using microsatellite markers to determine the genetic structuring among the species., Methods: A total of 15 microsatellite loci with M13 labeling were used for the genetic characterization of P. viridis along Indian waters. Genotyped data were analyzed using analytical software to determine the genetic stocks and understand the genetic variability across the populations., Results: We identified 15 polymorphic markers to understand the genetic stocks and variability across Perna populations. The mean value of the observed heterozygosity (Hobs: 0.741) for all populations was closer to the expected heterozygosity (Hexp: 0.75). The pairwise Fst values between the west and east coasts of India varied significantly, indicating the existence of significant genetic structure between the populations., Conclusions: Genetic stock identification using software analysis exhibited two distinct stocks, one along the west coast (Arabian Sea) and another along the east coast (Bay of Bengal). Bottleneck analysis indicated the genetic stability of species in the wild. P. viridis is a commercially vital species in Indian peninsular regions. The present study suggests the adoption of stock-specific relaying programs of the species from Indian waters in future studies., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Spanish mackerel S. commerson belonging to family Scombridae, represent a group of highly commercial marine fisheries with an ever-growing demand world over. Analysing the genetic diversity of this species is of utmost importance and necessary for conservation purposes. Microsatellites are molecular tools with advantages that are ideal for population analyses. This study provides the first multiplex panel set of species-specific microsatellite loci for S. commerson that can be applied when assessing both intra- and inter population genetic variation. Microsatellite marker panels were developed in S. commerson, using Third Generation Sequencing technology in PacBio RSII, based on Single-Molecule Real-Time (SMRT). Thirty- two microsatellite loci were isolated and characterized for S. commerson, by genotyping 20 individuals each obtained from the Kochi and Veraval in the Arabian sea and Chennai along Bay of Bengal coast (n = 3). The number of alleles per locus in S. commerson varied from 4 to 17, while the mean observed and expected heterozygosities ranged from 0.656 to 0.753. The Polymorphic Information Content (PIC) were highly informative, 85% loci with PIC value 0 > 0.75. This suite of markers provides the first species specific nuclear multiplex microsatellite marker panels (32 loci) for S. commerson and thus allows assessment of different populations structures of the species across its distribution range, with more specificity. These newly developed loci have also been validated for cross transferability in another scomberid fish Scomberomorus guttatus.

Perna viridis (Linnaeus, 1758), the Asian green mussel, belonging to the family Mytilidae is widely distributed along the Indian coast. The species is majorly found in southeastern countries and is considered an ideal candidate for aquaculture due to its high nutritional value and growth rate. Obtaining their genetic information is essential for their sustainable capture-based production. In the present study, genetic variation, population structure, and demographic processes of the populations across the distribution of this species were assessed using the mitochondrial DNA ATPase6 and cytb gene. In total, we selected 170 samples from five localities across the Indian subcontinent including Andaman Sea. Sequence analysis of partial cytb (885 bp) and ATPase6 (714 bp) genes revealed 45 and 58 haplotypes, respectively. The significant coefficient of genetic differentiation (F ST : 0.255 for cytb and 0.252 for ATPase6) and analyses of molecular variance indicated three varieties of stocks, namely Arabian Sea, Bay of Bengal, and Andaman Sea. All the populations showed low nucleotide diversity, suggesting severe historical bottleneck events and high haplotype diversity, indicating population expansion. The genetic variation and demographic process reported in this study will form the baseline information for framing policies, which can be adopted while planning stock specific ranching and relaying programmes in the Indian subcontinent with view to enhance and manage the fishery.

In the present study three species of mackerel, Rastrelliger present in Indian waters were taken for genetic identification using cytochrome c oxidase subunit I and 16s rRNA sequences. Accurate identification of these species is important for fishery management as its morphological characters are very similar. In this study, the sequences of COI and 16S rRNA were determined from 19 individuals of three Rastrelliger species, Rastrelliger kanagurta, Rastrelliger brachysoma and Rastrelliger faughni from Andamans and Indian mainland to study the phylogenetic relationship. The intraspecies and interspecies genetic distance ranged from 0.000 to 0.002 and 0.007 to 0.015 respectively based on 16S rRNA sequences. Using COI data analysis, the intraspecies genetic distance ranged from 0.000 to 0.012, while it varied from 0.039 to 0.086 for interspecies. The present study clearly demarcates three species of mackerel based on the mitochondrial genetic sequences and also showed a non-descriptive genetic distance of R. kanagurta from mainland and Andaman Islands.

Gonoproktopterus curmuca is an endangered red tailed barb found in Southern part of Western Ghat, India. As a part of stock-specific, propagation assisted rehabilitation and management program, polymorphic microsatellites markers were used to study the genetic diversity and population structure of this species from the three River systems of Southern Western Ghats, such as Periyar River, the Chalakkudy River, and the Chaliyar River. From selected eight polymorphic microsatellite markers, the number of alleles per locus ranged from 2 to 8, and the average number of alleles among 3 populations ranged from 5.0 to 5.75. The mean observed (Hob) and expected (Hex) heterozygosity ranged from 0.5148 to 0.5360 and from 0.5996 to 0.6067, respectively. Significant deviations from Hardy-Weinberg Equilibrium expectation were found at majority of the loci (except Gcur MFW72 and Gcur MFW19) and in all three populations in which heterozygote deficits were apparent. The analysis of molecular variance indicates that the percent of variance among populations and within populations were 6.73 and 93.27, respectively. The pairwise FST values between populations indicate that there were significant deviations in genetic differentiations for the red-tailed barb populations from these three Rivers of the Western Ghats, India. The microsatellites methods reported a low degree of gene diversity and lack of genetic heterogeneity in the population of G. curmuca, which strongly emphasize the need of fishery management, conservation and rehabilitation of G. curmuca.

The two species of yellow catfish, Horabagrus brachysoma and H. nigricollaris are categorized as 'endangered' and 'critically endangered' respectively in their wild habitat. Proper knowledge of genetic structure and variability of these endangered species are highly essential for the management, conservation and improvement of fish stocks. Therefore, genetic variation and phylogenetic relationships between these species of yellow catfish sampled from Chalakkudy River in the hot spot of biodiversity-Western Ghats region, Kerala, India were analyzed by using Random amplified polymorphic DNA (RAPD) and microsatellite markers. 85 RAPD and five microsatellites loci were detected to analyze the genetic variation and phylogenetic relationships among these species. Out of 85 RAPD loci produced only 52.94% were polymorphic whereas in microsatellite, all 5 loci were polymorphic (100%). Species-specific RAPD bands were found in both species studied. In microsatellite, the number of alleles across the five loci ranged from 1 to 8. The observed heterozygosities in H. brachysoma and H. nigricollaris were 0.463 and 0.443, respectively. Here, both RAPD and microsatellite methods reported a low degree of gene diversity and lack of genetic heterogeneity in both species of Horabagrus which strongly emphasize the need of fishery management, conservation and rehabilitation of these species.

Random amplified polymorphic DNA (RAPD) and microsatellite markers were applied to evaluate the genetic variation in endemic and endangered yellow catfish, Horabagrus brachysoma sampled from three geographic locations of Western Ghat, South India river systems. In RAPD, of 32 10-mer RAPD primers screened initially, 10 were chosen and used in a comparative analysis of H. brachysoma collected from Meenachil, Chalakkudy and Nethravathi River systems. Of the 124 total RAPD fragments amplified, 49 (39.51%) were found to be shared by individuals of all 3 populations. The remaining 75 fragments were found to be polymorphic (60.48%). In microsatellites, six polymorphic microsatellite loci were identified by using primers developed for Pangasius hypophthalmus, Clarias macrocephalus and Clarias gariepinus. The identified loci were confirmed as microsatellite by sequencing after making a clone. The nucleotide sequences of 6 loci were published in NCBI genbank. The number of alleles across the six loci ranged from 4 to 7 and heterozygosities ranged from 0.07 to 0.93. The mean number of alleles and effective number of alleles per locus were 5.00 and 3.314, respectively. The average heterozygosity across all investigated samples was 0.72, indicating a significant deficiency of heterozygotes in this species. RAPD and microsatellite methods reported a high degree of gene diversity and genetic distances depicted by UPGMA dendrograms among the populations of H. brachysoma.