DETERMINATION OF ELECTROPHORETIC VARIATIONS IN THE ISOZYME SYSTEM OF THREE CLARIID SPECIES

Abstract

This study was conducted to determine the genetic characteristics and variations within and among the three employed clariid populations; the horizontal starch gel electrophoresis was used. Moreover, morphometric characteristics were measured to determine the proportions that can be accounted for by the genetic factors influence to the measured characters.

Preliminary test showed skeletal muscle exhibiting good resolution and maximum loci activity. Five proteins employed in the study resolved six loci that modally migrated viz., ADH-I, IL-I, SOD-I, IDDH-1,2 and NOH-I *. Except for 101--1-1 *, all other loci were monomorphic. Observed heterozygosity reflected high in C. batrachus (HL = 0.50); low in C. macrocephalus (HL 0.44); and none of C. gariepinus (HL = 0.00). Within-population genetic variations revealed C. batrachus (1² = 0.22 p<0.05) conforming to the HardyWeinberg Law, while C. macrocephalus (1² =14.89 p>0.01) and C. gariepinus (12 = 54.00 p>0.01) significantly deviated from the expected proportions. Intra - and interspecific variations observed were attributed to heterozygote deficit, restricted effective population size, founder effects, Wahlund effects and even to anthropogenic influence. Genetic factors influence to the measured morphometric characteristics reflected low results, ranging from 0.6% for BD to 37% for BG, suggesting that the environment influenced the large proportions.

The results are of value to conservation authorities, researchers, and aquaculturists concerned with commercial species production.