THE DYNAMICS OF GENETIC VARIABILITY IN THREE GENERATIONS OF MASS SELECTION FOR FAST GROWTH IN AFRICAN CATFISH, Clarias gariepinus ASSESSED BY MICROSATELLITE MARKERS
Abstract: Selective breeding
aiming at improving the performance of economically important traits acts by
exploiting population’s phenotypic variance. Due to the relationship between
phenotype and genotype, selection on phenotype may also affect the profile of genotype.
This study was aimed to monitor the impact of three generations of mass
selection for fast growth in African catfish, Clarias gariepinus, on genetic
variability, assessed by microsatellite. A total of 350 fish representing four
populations, namely a composite base population (G-0), selected lines of the
first generation (G-1) to the third generation (G-3), were sampled. The samples
were screened for their genetic diversity using five microsatellite loci1
namely cga01, cga02, cga03, cga05, and cga09. Several genetic parameters
including number of allele (A), allelic richness (AR), observed (Ho) and
expected (He) heterozygosity, and fixation index (Fis) were evaluated. The
results showed that there was a slight increase in the value of diversity indices
in the G-1 relative to the G-0 and to the other two generations. Among these
parameters, the number of allele seemed to be the most sensitive parameter in
detecting genetic changes. All populations experienced heterozygote deficit and
positive fixation index indicating the phenomena of inbreeding. Overall,
selection for growth for three generations in African catfish breeding program
resulted in significant genetic differentiation between populations. Further,
the level of genetic differentiation seemed to accumulate along with the number
of generaton in breeding program. However, selection did not result in a
decline in genetic diversity within population. A relatively short period of
the program, along with the use a high number of broodstock (mating pairs) to
produce each generation seems to be able to maintain the stability of genetic
diversity of the population.
Keywords: genetic changes;
Clarias gariepinus; microsatellite; mass selection
Author: Imron, Bambang Iswanto, Huria Marnis, Rommy
Suprapto, Narita Syawalia Ridzwan
Journal Code: jpperikanangg150051
