EFFECTS OF DOMESTICATION ON GENETIC-VARIABILITY, FERTILITY, SURVIVAL AND GROWTH-RATE IN A TROPICAL SILURIFORM - HETEROBRANCHUS-LONGIFILIS VALENCIENNES 1840

Fertility, survival rate, larval growth, as well as genetic variabilit y at 23 loci, were analyzed in two populations representing the first and fourth generations of the African siluriform Heterobranchus longif ilis Valenciennes 1840. A loss of genetic variability was observed in the fourth generation as compared to the first generation, and in the first generation as compared to the wild population studied earlier. T herefore, for 23 loci studied, only one single polymorphic locus with two alleles was observed for the fourth generation, two polymorphic lo ci with two alleles for the first generation. The first generation str ain is characterized by a lower rate of deformed fry and greater survi val to the 14th day compared to those of the fourth generation strain. This difference in the survival rate did not permit clear interpretat ion of the differences observed in growth rates. A study measuring the effect of stocking density on growth rate showed the negative correla tion between stocking density and growth rate. These results show that H. longifilis is a species for which domestication may lead to loss o f genetic variability and decreases in performance.