Low allozyme variation in tigerfish Hydrocynus vittatus (Teleostei: Alestidae) from the Okavango panhandle, with notes on the selection of candidates for artificial breeding

Abstract

To ensure the utilisation of optimal tigerfish gene pools for artificial propagation, the hypothesis that tigerfish from the Okavango system should have greater heterozygosity than those from smaller river systems was tested. This electrophoretic analysis provides the first report of the quantity and pattern of genetic variation for tigerfish of the Okavango Delta to be considered for artificial propagation and as candidates for an evolutionary significant unit. Mean heterozygosity was 1% in the Okavango, as compared to 1.9% in the Upper Zambezi and 5.6% in the Olifants River systems. Possible reasons for this anomaly, in terms of the Hardy-Weinberg principle, include the founder  effect caused when the Okavango and Zambezi rivers became separated, and/or that the Okavango is a more stable system and  therefore that a large variation might not be required in its individuals for survival. Significant differences of genotypes were found among all populations previously studied. The selection of potential candidates for artificial breeding is discussed.

Keywords: electrophoresis; genetic variation; heterozygosity; Okavango Delta; Olifants River; Zambezi River

African Journal of Aquatic Science 2009, 34(3): 249–254