Molecular characterization of Clarias gariepinus from the Nile and an inland Lake, Sudan

Genetic diversity and population structure of Clarias gariepinus were evaluated by analyzing genetic distances among Sudanese populations and comparing them with reference sequences obtained from GenBank.Pairwise genetic distance (π) estimates indicated substantial variation, ranging from complete genetic identity (π = 0.000) to moderate divergence (π = 0.056).The greatest genetic distance was recorded between the Al-Rahd 2 population and an Indian reference sequence (KX946613), reflecting notable genetic differentiation.Similarly, Al-Rahd 2 exhibited relatively high divergence (π = 0.048) from populations originating in North Korea, Thailand, Congo, Brazil, and Bangladesh, suggesting possible historical isolation, limited gene flow, or distinct evolutionary trajectories.Conversely, several Sudanese populations demonstrated very low to zero genetic divergence when compared with global reference sequences.Abu-Gasba 1, Khashm Al-Girba 3, and Sennar 2 were genetically identical (π = 0.000) to sequences from Egypt and Indonesia.In addition, Abu-Gasba 1 and Khashm Al-Girba 3 showed complete genetic similarity with populations from a broad geographic range, including Nigeria, Ethiopia, Uganda, China, Turkey, Bangladesh, and India.This widespread genetic uniformity suggests strong connectivity and dispersal across regions.A slightly elevated but still minimal genetic distance (π = 0.002) was observed between Khashm Al-Girba 4 and several Asian and African reference populations.The findings reveal a combination of localized genetic differentiation and extensive genetic homogeneity in C. gariepinus, highlighting patterns of dispersal, introduction, and population connectivity.