The mitochondrial genome of an endangered native Singidia tilapia, Oreochromis esculentus: genome organization and control region polymorphism

Abstract

Singidia tilapia (Oreochromis esculentus) is a native Cichlid fish of important commercial value, distributed in Lake Victoria, East Africa. Due to its declining population levels in its natural habitat, this species has now been classified as a Critically Endangerd by the International Union for the Conservation of nature (IUCN). In the present study the complete nucleotide sequence of the mitochondrial genome (mtDNA) of O. esculentus was determined. In addition, polymorphism analysis based on the mtDNA’s control region sequence was investigated on two of its remaining populations of Yala and Borabu as well as a phylogenetic consideration using 16S rRNA mtDNA genes to explore its position and relationship within Cichlidae fish. The length of the complete mitogenome of O. esculentus is 16 622 bp, containing the same order and an identical number of genes and regions with the other reported Cichlid fishes, which consists of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a putative non-coding region. The phylogenetic analysis shows O. esculentus being clustered within the Oreochromini sub-tribe of the Cichlidae. The high genetic diversity and low genetic differentiation between the two populations indicated the need for conservation of both the refuge ecosystems and the fish species under study.