Mitogenomic Composition And Phylogenetic Analysis Of Lutjanus Fulgens Identified By DNA Barcoding From Some Commercial Marine Fish Species From Ghana In West Africa

Molecular genetics has evolved as an essential tool in the study of taxonomy and systematics of living organisms.Different fish species exist in the various aquatic system which require thorough research based on their genetic composition to accurately identify them and understand their evolutionary relationships and subsequently plan specific management measures to manage them sustainably for posterity.This study employed some recognized next generation sequencing technologies and approaches to sequence,assemble and analyze the COI genes(DNA barcodes)of Lutjanus fulgens,Epinephelus costae,Sardinella maderensis,Sardinella aurita,Pseudotolithus typus,Pseudotolithus senegallus,Pseudotolithus elongatus,Pagellus bellottii,Pagrus caeruleostictus and Epinephelus aeneus.Furthermore,the complete mitochondrial DNA of Lutjanus fulgens and Pagrus caeruleostictus were sequenced and scrutinized.Lastly,a phylogenetic study of the genus Lutjanus was conducted based on mitogenomic and COI gene sequences.All these species are fishes living in the Eastern Atlantic Ocean including the shoreline of Ghana.The general findings of this research are summarized as follows;I.Molecular-based identification and analysis of some economically important marine fish species as revealed by mitochondrial DNA COI gene from Ghana,West AfricaMolecular-based species identification is a method employed by molecular taxonomists and other scientists to identify species using the genetic material/ genes of the subject or to understand the evolution of genes and to analyze the population genetics of organisms.The COI and 16 S r RNA genes are some prominent genes often employed to measure the degree of molecular differentiation amongst organisms in such a molecular-based approach to distinguish species.Several researchers have confirmed the accuracy of DNA barcode as a species identification tool.The Ghanaian marine environment,located in the Eastern Atlantic,accommodates a highly diverse fish stock.This possesses great difficulty with regards to accurate species evaluation and stock inventory hence the need for advanced species discriminatory methods such as DNA barcoding.In this research,a total of 120 specimens which consisted of Lutjanus fulgens,Epinephelus costae,Sardinella maderensis,Sardinella aurita,Pseudotolithus typus,Pseudotolithus senegallus,Pseudotolithus elongatus,Pagellus bellottii and Epinephelus aeneus were taken from the coast of Ghana.Their DNAs were purified with the Ezup Column Animal Genomic DNA purification procedure integrated with proteinase K digestion method and afterwards sequenced with Sanger sequencing technology.One hundred and five(105)COI genes were successfully sequenced while 15 specimens failed to be sequenced.Then,MEGAv6.0 software was employed to edit erroneous nucleotides and analyzed the sequence along with the performance of K2 P statistics and phylogeny study using neighbour joining(NJ)algorithm.Moreover,DNASP software was utilized to check the sequence polymorphism.The findings of this study depict that,geographically,L.fulgens,Pagellus bellottii and Pseudotolithus typus inhabit only at the eastern part of the country.Likewise,Epinephelus costae and Epinephelus aeneus were localized species of the eastern and western parts respectively of the country.However,Sardinella maderensis,Sardinella aurita,Pseudotolithus senegallus,and Pseudotolithus elongatus exist at both sides.These results could be due to the small sample size.But,as expected,the COI gene formed clusters with respect to the species in the phylogeny study where the clades of species of the same genus were closer clades in the tree.From the results,the morphologically identified species were positively confirmed upon cross-reference with the data available on Gen Bank and BOLD Systems.Furthermore,the sequence polymorphism analysis of the COI gene showed the presence of at least 2 haplotypes in each data set.These haplotypes suggest the existence of a possible cryptic linage diversity in all the sampled species from both the western and eastern sides of the country.This study is a novel study for these species found in Ghana,so it builds the foundation for future molecular-based study and as a DNA barcode reference data for these species in the Ghanaian marine environment.This will aid future ichthyofaunal diversity studies to enhance marine fishery management and conservation in the country.II.Complete mitochondrial genome and composition of Lutjanus fulgens(Valenciennes,1830)and Pagrus caeruleostictus(Valenciennes,1830)Lutjanus fulgens(Valenciennes,1830)is a teleost species classified under the family Lutjanidae which is a native of the Eastern Atlantic Ocean.Though highly commercialized due to its abundance and good taste,the production output has declined in recent years.This is an indication of the need for effective management and conservation measures.However,understanding the genomic dynamics,evolution and accurate species identification can assist strategic management and conservation design.DNA-based species identification and species adaptation evaluation have proven their reliability in the area molecular analysis of organisms.Several researchers have confirmed the precision of molecular-based species identification and species phylogeny analysis with the use of the complete mitogenome.Currently,specimen of the Golden African snapper was sampled from Ghana and subjected to DNA-based analysis,precisely,the complete mitochondrial DNA scrutiny.The mitogenomic result revealed that L.fulgens is made up of a 16,500 base pairs(bp)mt DNA which consists of 22 transfer RNAs,13 protein coding genes,and two ribosomal RNAs(Gen Bank Accession Number: MN398650).Moreover,the Bluespotted seabream(Pagrus caeruleostictus),a recognized marine fish species usually found in the benthopelagic zone of the sea in tropical regions and classified as a member of the genus Pagrus,was also sampled.Here,DNA sequencing was carried out on muscle and determined the complete mitogenome.The complete mitochondrial DNA sequence was also16,653 bases pairs in length(Gen Bank Accession number: MN319701)and comprises of 37genes;22 transfer RNA genes,2 ribosomal RNA genes,13 protein coding genes along with a control region.This was similar to that of L.fulgens and other Perciformes’ mitochondrial DNA.This research provides the groundwork for any future molecular genetic studies of these two fish species.Moreover,it contributes to the systematics and taxonomy of class Actinopterygii,order Perciformes,families Lujanidae and Sparidae,and genus Lutjanus and Pagrus.Both fish species are populaces of the Eastern Atlantic Ocean and are highly marketed due to their great taste and abundance.III.Phylogenetics of Lutjanus fulgens and other Lutjanidaes based on the completed mitochondrial DNA and COI gene sequences.Phylogenetic study is a pivotal aspect in the study of species evolutionary relationships usually within and between taxonomic group of organisms via the use of genetic components such as genes and DNA sequences.This approach is used by geneticists to evaluate cryptic speciation caused by an array of events such as mutation,reduced gene flow,hybridization and geographic isolation,phylogenetics becomes an essential tool to unravel the mystery of speciation.Major phylogenetic algorithms including K2 P genetic distance model and maximum likelihood were employed for a detailed genetic diversity and phylogenetic analysis within the family Lutjanidae to establish the evolutionary descent between these Lutjanus species.The complete mitochondrial DNA and COI gene sequences were the genetic materials utilized.MEGAX software was used to align the sequences with the Clustal W alignment option and subsequently generated a K2 P genetic distance table based on COI genes and constructed a ML tree for both the mitogenome and COI sequences separately.The findings of this analysis indicated a close taxonomic relationship exists between L.fulgens and L.buccanella,L.analis,L.synagris,and L.guttatus but a closer relationship with L.buccanella due to the small genetic distance(0.047)as compared to the genetic distance with other the sister species.This suggests a recent speciation between these two fish species.Based on their location,it is speculated that this could be a sympatric speciation.