DNA Barcoding of Tilapia Species (Pisces: Cichlidae) from North-Eastern Nigeria

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The Tilapiine complexes are made up of diverse species, hence the need for proper identification. Samples of tilapia species belonging to the family of Cichlidae obtained from Upper Benue River and Lake Geriyo landing sites were used for this study. Fish species were morphologically identified in situ by visual inspection with the aid of field guide for taxonomic studies. DNA was extracted from fresh fish tissue and the barcode gene region cytochrome c oxidase subunit 1 (co1) was amplified using the FishF1 and FishR1 primer pair. Amplified products were visualized on 1% agarose gel electrophoresis, purified and sequenced using Genetic Analyzer (Applied Biosystems 3130 XL). Four species (Oreochromis niloticus, Sarotherodon galilaeus, Sarotherodon galilaeus boulengeri and Coptodon zillii) belonging to three genera (Oreochromis, Sarotherodon and Coptodon) were identified in the study area. From our sampling survey, Oreochromis niloticus was the most dominant species in both areas, followed by Coptodon zillii. Sarotherodon spp. was not present in Upper Benue River but present in Lake Geriyo (an ox-bow lake of Upper Benue River). A new sub-species of Sarotherodon galilaeus known as Sarotherodon galilaeus boulengeri was identified in this study from the sequencing result. This species has never been reported in any literature to be present in Nigeria, which further confirmed the efficacy of DNA barcoding in the identification of cryptic species. The phylogenetic relationship and genetic distance between generic groups obtained in this study was in concordance with the hypothesis of Trewavas that the mouth brooders Orechromis niloticus and Sarotherodon galilaeus are more closely related to each other than the substrate brooders (Tilapia zillii).