40 GENERATIONS OF BIDIRECTIONAL SELECTION FOR MATING FREQUENCY IN MALE JAPANESE-QUAIL

A bidirectional replicated selection experiment for high (H1 and H2) o r low (L1 and L2) cumulative number of complete matings (CNCM) in male Japanese quail was conducted for 40 generations. In the S-32 generati on a subline was taken from each selected line and selection was relax ed. Ln the randombred control line (C), CNCM and unselected traits cha nged significantly over generations. Means of the selected lines were adjusted each generation for deviations from the control means. After 40 generations of selection, there was a 21-fold difference in CNCM (5 9.4 vs 2.8) between Lines H1 and L1. Whereas means increased and varia tion decreased in the high lines, means decreased and variation increa sed in the low lines. Regressions of mean CNCM on generation of Lines H1, H2, L1, and L2 were 1.15 +/- 0.08, 0.61 +/- 0.08, -0.26 +/- 0.04, and -0.34 +/- 0.03, respectively. Although responses to selection were observed throughout the 40 generations in Line H1, the low lines appe ared to have reached a limit to selection after the S-30 generation. R elaxed lines provided supporting evidence for this conclusion. Mean CN CM decreased in the relaxed high lines to that of the control, whereas the low relaxed lines remained at the same level as their correspondi ng selected lines. Line H2 went into extinction in the 37th generation as a result of reduced fitness. Realized heritabilities of CNCM were 0.09, 0.07, 0.06, and -0.15 in Lines H1, H2, L1, and L2, respectively. As correlated responses to the selection, male quail in the high line s were heavier, exhibited greater relative aggressiveness, and had lar ger cloacal glands than those of the control and low lines.