Genetic diversity, population genetic structure and demographic history of the Ribbontail stingray Taeniura lymma (Fabricius, 1775) (elasmobranchii: myliobatiformes: dasyatidae) along the Tanzanian coastline.

The Ribbontail stingray Taeniura lymma is an economically important fish and attractive species for the aquarium trade industry. Overfishing, habitat degradation, and pollution, however, pose a threat to this species. This study used partial mitochondrial cytochrome oxidase subunit I (COI) sequences (603 base pairs long) from 96 samples of T. lymma collected at five fish-landing sites (Deep Sea-Tanga, Malindi-Unguja, Kaole-Bagamoyo, Kivukoni-Dar es Salaam, and Bandarini-Mtwara) located along the coast of Tanzania to determine the species' genetic diversity, population genetic structure, and demographic history. The findings revealed an average nucleotide diversity of 0.24 ± 0.16% and a haplotype diversity of 0.75 ± 0.04. Nucleotide and haplotype diversities were relatively low at Kaole-Bagamoyo compared to the other studied localities. An Analysis of Molecular Variance (AMOVA) indicated limited but statistically significant genetic differences among populations (Overall F_ST = 0.09, p < 0.01). Pairwise AMOVA revealed genetic difference between the Deep Sea-Tanga population and all other populations studied with exception of Malindi-Unguja. Analyses of mismatch distribution, demographic history, and a haplotype network support a scenario of historical population expansion in the studied species. Immediate effort is required to protect population exhibiting low genetic diversity in this commercially important ray.