Changes of protein polymorphism in selection program for egg production in Japanese quail, Coturnix coturnix japonica, 2: Gene constitution of 8th and 13th generations
1999
Maeda, Y. (Kagoshima Univ. (Japan). Faculty of Agriculture) | Minvielle, F. | Okamoto, S. | Hashiguchi, T.
The present study was conducted to evaluate the changes of gene constitution and genetic variability at 8th and l3th generations of individual and reciprocal recurrent selection experiments for egg production using Jouy and Tours strains of Japanese quail maintained in INRA. Genetic variability was analyzed for 6 lines (lines l, 2, 3, 4, C and D) of both strains by 10 protein loci. Proportions of polymorphism (Ppoly) decreased with advancing generation, but it remained bigger in Tours lines, as the values at generations 1, 8 and 13 were 0.5-0.6, 0.4-0.5 and 0.3-0.4 in Jouy lines, and 0.7, 0.6-0.7, and 0.5-0.7 in Tours lines, respectively. The GsT among 6 lines were 0.019, 0.076 and 0.156 at generation 1, 8 and 13, respectively. Increasing GsT value with advancing generation suggests that subdivision among lines was progressing. From various comparison of GsT, it appeared that some genetic differentiation gradually took place during the experiment and that this subdivision partly resulted from differences in the breeding system. On the PC1 axis of principal component analysis, the 6 lines were separated broadly in three groups (lines 1 and 2 under individual selection, lines 3 and C of Jouy strain, and lines 4 and D of Tours strain) at generation 8, and are now clearly separated in groups as control lines (lines C and D), individual selection lines (lines 1 and 2) and reciprocal recurrent selection lines (lines 3 and 4) at generation 13. Results of genetic distance suggest that selection for 13 generations in the present study was accompanied by increased genetic diversity among INRA lines, possibly through the compound effects of the mode of selection (direct and recurrent selection) and of genetic drift (small population size)
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