Morphometric And Dna Variation Of The African Catfish (Clarius Gariepinus) In Selected Cultured And Wild Populations In Kenya

Abstract

The study seeks to define and understand the population diversity, morphological and genetic differences of these fish in their natural habitats from which brood stock is obtained and in hatcheries in Kenya. Catfish samples were obtained from six sites in the country namely Athi River hatchery, Kisii Fingerling Production Centre (FPC), Jewlett hatchery, Sagana Station, Lake Baringo and Lake Naivasha. The samples were characterized using morphometric and genetic markers. For morphometric study, canonical variate and principal component analyses were used to cluster the populations in Genstat and SPSS so as to determine population variation. Thirteen variables of one hundred forty-five African catfish were subjected to the analyses for morphological characterization. For molecular study, DNA was extracted from the muscle tissue samples, followed by amplification and sequencing of the D-loop region of mitochondrial DNA. The sequences were subjected to diversity analyses in MEGA 7, DNASP V5 and Arlequin V3.5. Morphometric clustering of fish was evident with four populations having an overlap in clusters i.e. Kisii, Jewlett, Sagana and Baringo. The Naivasha and Athi River population did not overlap. The two clustered distantly from each other and from the overlapped three populations. Diversity as derived from mitochondrial DNA markers for the populations as a whole was Hd: 0.884 ±0.017 and the nucleotide diversity (π) was 0.09018± 0.10414. The diversity in each site population varied with Baringo having the highest at 0.913±0.035 while Naivasha had no diversity at 0.00±0.00. The Naivasha population had only one haplotype while the others had more than one haplotype. xiii The genetic and morphometric results were congruent confirming the results. The Sagana, Kisii FPC, Jewlett and Baringo population overlapped when assessed using both morphology and genetic methods indicating possibly shared source of broodstock. The Naivasha populations being distinct is not likely to have originated from the catfish in the other sampled sites or could have undergone mutations in the region resulting in the high differentiation. The Athi River population was distant and distinctiveness is attributed to imported broodstock. The Athi River hatchery population and Lake Baringo population have the highest diversities hence should be targeted as source of fingerlings.