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

摘要

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.