A. Gopalakrishnan

Mitochondrial ATPase 6/8 genes to infer the population genetic structure of silver pomfret fish Pampus argenteus along the Indian waters

Abstract Silver pomfret, Pampus argenteus is an economically important seafood species. The fishery resource of pomfret in Indian waters shows a dwindling catch since the last few years and the pomfrets caught were mostly undersized which calls for immediate attempts for management of resources. An accurate definition of population structure is important for management of this species. The genetic stock structure of P. argenteus distributed along Indian coast was identified using analysis of 842 bp of complete ATPase 6/8 genes of mitochondrial DNA. Altogether, 83 silver pomfret (P. argenteus) collected from 4 locations along Indian coast (Gujarat, Kerala, Tamil Nadu and West Bengal) were sequenced. Twenty four haplotypes were identified among 83 individuals with haplotype diversity (0.87) and nucleotide diversity (0.0025). The significant pair-wise FST and AMOVA values, between samples from West Bengal (east coast) and other locations along the west coast (Gujarat and Kerala) indicated the occurrence of distinct population structure in silver pomfret along the coast.

Molecular phylogenetics of three species of the genus Rastrelliger using mitochondrial DNA markers

Abstract 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.

Microsatellite Markers to Determine Population Genetic Structure in the Golden Anchovy, Coilia dussumieri

Coilia dussumieri (Valenciennes, 1848) commonly called as golden anchovy, constitutes a considerable fishery in the northern part of both the west and east coasts of India. Despite its clear-cut geographic isolation, the species is treated as a unit stock for fishery management purposes. We evaluated 32 microsatellite primer pairs from three closely related species (resource species) belonging to the family Engraulidae through cross-species amplification in C. dussumieri. Successful cross-priming was obtained with 10 loci, which were sequenced for confirmation of repeats. Loci were tested for delineating the genetic stock structure of four populations of C. dussumieri from both the coasts of India. The number of alleles per locus ranged from 8 to 18, with a mean of 12.3. Results of pairwise FST indicated genetic stock structuring between the east and west coast populations of India and also validated the utilization of identified microsatellite markers in population genetic structure analysis.

Genetic identification and phylogenetic relationships of Indian clariids based on mitochondrial COI sequences

Abstract Mitochondrial cytochrome C Oxidase I (COI) sequence variation among the clariid fishes of India (Clarias magur, C. dussumieri and C. gariepinus) and their relationship with other representative clariids was studied in this work. Three species were sampled and together with 23 COI sequences from GenBank were used to reconstruct phylogenetic relationships in the family Clariidae. The study revealed two clades: one consisting of the African species with C. dussumieri, and the other of Asian species suggesting the prevalence of intra-continental diversification of catfishes. This study further revealed that the genus Clarias is monophyletic. For the COI gene, the interspecies genetic divergence ranged from 0.056 to 0.182. The mean genetic difference between C. dussumieri and other selected African species in this study is 12.1%. It was also observed that the morphological similarity of C. dussumieri and C. magur was not replicated in the genetic level. Clarias dussumieri was more close to African catfish C. gariepinus thus indicating the utility of COI phylogeny to identify the well-known African-Asian relationships within catfishes. The results also showed that C. magur and C. batrachus are genetically distinct from each other.

Hints for panmixia in Scomberomorus commerson in Indian waters revealed by mitochondrial ATPase 6 and 8 genes

Abstract Scomberomorus commerson is an economically important migratory fish distributed worldwide. The genetic stock structure of S. commerson distributed along the Indian waters was identified using mitochondrial ATPase 6 and 8 genes. A total of 842 bp sequence of ATPase 6/8 genes obtained in this study revealed 23 haplotypes with mean low nucleotide diversity and high haplotype diversity. Co-efficient of genetic differentiation (FST) values obtained for pair wise populations were low and non-significant with an overall value of −0.02074. The high haplotype and low nucleotide diversity values together with mismatch distribution analysis suggested a history of genetic bottleneck events or founder effect, with subsequent population expansion in S. commerson. The findings of the present study indicated the panmixia nature of the species which can be managed as a unit stock in Indian waters.

Molecular identification of Bigeyes (Perciformes, Priacanthidae) from Indian waters

Abstract Thirty-five individuals of six priacanthid fish species were sampled from different localities along the coast of India covering the Arabian Sea and Bay of Bengal. The partial sequence of 16S rRNA and cytochrome oxidase subunit I (COI) genes were analyzed for species identification and phylogenetic relationship among the Indian priacanthids (Priacanthus hamrur, P. prolixus, P. blochii, P. sagittarius, Cookeolus japonicus, and Pristigenys refulgens). The intraspecies genetic distance ranged from 0.000 to 0.002, while distances varied from 0.008 to 0.157 interspecies based on 16S sequences. Using COI data analysis, the intraspecies genetic distance ranged from 0.000 to 0.005, while interspecies distances varied from 0.009 to 0.108. Several sequences labeled Priacanthus hamrur in GenBank are shown to be P. prolixus. We also observed cryptic speciation in Heteropriacanthus cruentatus. Partial sequences of 16S rRNA and COI genes provided phylogenetic information to distinguish thirteen species of priacanthids, indicating the usefulness of molecular markers in species identification.

Molecular phylogeny of commercially important lobster species from Indian coast inferred from mitochondrial and nuclear DNA sequences

Abstract Lobsters constitute low-volume high-value crustacean fishery resource along Indian coast. For the conservation and management of this declining resource, accurate identification of species and larvae is essential. The objectives of this work were to generate species-specific molecular signatures of 11 commercially important species of lobsters of families Palinuridae and Scyllaridae and to reconstruct a phylogeny to clarify the evolutionary relationships among genera and species included in this study. Partial sequences were generated for all the candidate species from sampling sites along the Indian coast using markers like Cytochrome oxidase I (COI), 16SrRNA, 12SrRNA, and 18SrRNA genes, and analyzed. The genetic identities of widely distributed Thenus species along the Indian coast to be Thenus unimaculatus and the sub-species of Panulirus homarus to be P. homarus homarus were confirmed. Phylogeny reconstruction using the individual gene and concatenated mtDNA data set were carried out. The overall results suggested independent monophyly of Scyllaridae and Stridentes of Palinuridae. The interspecific divergence was found to be highest for the 12SrRNA compared with other genes. Significant incongruence between mtDNA and nuclear 18SrRNA gene tree topologies was observed. The results hinted an earlier origin for Palinuridae compared with Scyllaridae. The DNA sequence data generated from this study will aid in the correct identification of lobster larvae and will find application in research related to larval transport and distribution.