Evaluation of Genetic Variation in Oreochromis Tilapia Species from South-South Nigeria using Mitochondrial DNA Hypervariable Region.

Understanding genetic variation among species is essential for effective selection and breeding enhancements. This study was conducted to assess the genetic diversity among three tilapia species (Oreochromis niloticus, Oreochromis aureus, and Oreochromis mossambicus) from several rivers located in South-South Nigeria. A total of 300 samples representing the three species were used for this research. Blood samples were collected from all individuals for DNA extraction, amplification, and sequencing of the mitochondrial (mt) control region. Analysis of mitochondrial DNA revealed that Oreochromis aureus exhibited the greatest number of polymorphic sites, with a total of 225, compared to Oreochromis niloticus and Oreochromis mossambicus, which had 129 and 84 polymorphic sites, respectively. The number of haplotypes was highest in O. niloticus with five, while O. aureus and O. mossambicus each had three haplotypes. O. niloticus also demonstrated the highest haplotype diversity (0.796), whereas O. aureus showed the highest nucleotide diversity (0.139). The largest genetic distance was found between O. aureus and O. mossambicus (0.388), whereas the smallest genetic distance was noted between O. niloticus and O. mossambicus (0.217). Enhancing tilapia production in Nigeria can be achieved by selectively breeding tilapia from the Itu, Ethiope, and New Calabar Rivers, which exhibited high genetic variation. [ABSTRACT FROM AUTHOR]