RELATIONSHIPS BETWEEN GENETIC-DISTANCE AND DOMINANCE AND EPISTATIC EFFECTS IN LINE-CROSSES OF MICE

From each oi two populations, the outbred NMRI(N) and the synthetic fo ur-way cross (S), a line was selected for high 8-week body weight (N8, S8), one for low 8-week body weight (N6, S6) and one line served as c ontrol (N9, S9). One N line was selected for an antagonistic goal,high 3-5 week gain and low 8-week body weight. After 54 generations of sel ection lines were crossed and F1, F2 and backcrosses produced. From th ese the generic effects, additive, dominance, additive x additive (axa ) and (additive x dominance) (axd) epistatic, were estimated. Based on che frequencies of nine biochemical markers, generic distances as pro posed by Cavalli-Sforza and Nei were estimated. between the lines. Dom inance and epistatic effects Increased with distance. Adding a quadrat ic term raised the statistical significance of distance on axa effects to near 0.10. When the marker distance was supplemented with a distan ce caused by selection the statistical significance of the predictor f or axa of Loth 5-8 week gain and BW8 passed 0.05.