Large allozyme variation within populations and isozyme differences between Clarias gariepinus and C. ngamensis from the Okavango Delta, Botswana

Abstract

An allozyme study of 47 Clarias gariepinus and 53 C. ngamensis individuals revealed variation at 11 (57.9%) and eight (40%), out of 19 and 20 loci, respectively. The average heterozygosity of 0.167, 57.9% polymorphism and average of 1.895 alleles at loci is the largest amount of variation yet reported for C. gariepinus. Significant pair-wise contingency chi-square differences, one isozyme and another fixed allele difference at LDH, were found between the species. Nevertheless, a relatively small genetic distance value (D = 0.134) between the species supports recent morphological and DNA results by other researchers, confirming the closeness of these two species.