A comparison of allozyme heterozygosity and life history variables in four strains of african catfish (clarias gariepinus)

Abstract

Summary We studied allozyme polymorphism and its relation to morphological characteristics in 122 individuals from four lines of African catfish. Starch gel electrophoresis was used to screen 26 loci, of which five were polymorphic. Average heterozygosity levels differed moderately among lines (range 4–6.3 %) and were closely related to the management histories of the populations studied. Significant differences between the allelic frequencies of strains were found at all polymorphic loci, and gene products of glucose-6-phosphate isomerase (E.C. 5.3.1.9) proved particularly suitable for differentiation among the four strains studied. There was little evidence for linkage between heterozygosity values and specific quantitative morphological characteristics. However, a significant positive correlation between heterozygosity and variation within the morphological parameters involved was found in several instances.