COMPARATIVE MITOCHONDRIAL DNA (MTDNA) OF OREOCHROMIS VARIABILIS AND TILAPIA ZILLI: GENOME CHARACTERIZATION AND PHYLOGENY ANALYSIS.
Cichlid fishes have played an important role in evolutionary biology, population studies, fisheries and aquaculture industry. In addition, the East African species represents a model suited for studying genetic resources conservation, adaptive radiation and speciation where closely related genomes are fast emerging presenting gene pools and queries on phenotype-genotype correlations. The current study employed genome sequencing techniques to extract, assemble, sequence and analyze fish mitochondrial DNA (mtDNA) genomes for two closely related but eco-morphologically highly distinct Lake Victoria basin cichlids. Cichild fish species Victoria tilapia (Oreochromis variabilis) is an endangered native species while Redbelly tilapia (tilapia zilli) is an invasive exotic species that continues to colonize and occupy a variety of habitats within the Lake Victoria basin. Results from this study show that mtDNA sequence of Oreochromis variabilis is 16 626 bp long and that of Tilapia zilli is 16 619 bp long both of which consists of 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a control region (CR), with an overall sequence similarity of 91%. Furthermore, phylogenetic analyses of the two species reveal a remote sub-tribe relation within family Cichlidae. Therefore these species can be placed into different clades according to their biogegraphical origin and distribution. Emanating from this study, the availability of additional molecular information on complete mtDNA sequences of cichlids may provide an opportunity to interpret the dynamics of genome evolution in ancient fish lineages along with their applications in fish genetic resources conservation, aquaculture breeding programmes, ecology and evolutionary studies.