Single-trait and antagonistic index selection for litter size and body weight in mice.
Single-trait and antagonistic index selection for litter size and body weight in mice.
复制标题
小鼠产仔数和体重的单性状和拮抗指数选择。
作者：
E. J. Eisen
仅基于雌性表现的个体选择在四系小鼠中进行：L(+)表示增加产仔数，W(+)表示增加6周体重，L(-)W(+)表示旨在减少产仔数和增加6周体重的选择指数，L(+)W(-)表示旨在增加产仔数和减少6周体重的选择指数。第五行 (K) 作为未选择的对照。所有窝的小鼠在一日龄时均标准化为八只。预期遗传力基于母体 (h(2) (d)) 后代回归的两倍，其中包含由于直接 (sigma(2) (A(o) )) 和母体 (sigma(2) (A(m) )) 效应及其协方差 (sigma(A(o)A(m) )) 造成的加性遗传方差。测量响应和相关响应偏离控制线（方法 1）或不偏离控制线（方法 2）。产仔数的实际遗传力 (h(2) (R)) 为 0.19 +/- 0.04 (1) 和 0.16 +/- 0.03 (2)，与 h(2) (d) 的 0.17 +/- 0.04 相似。 6 周体重的 h(2) (R) 为 0.55 +/- 0.07 (1) 和 0.44 +/- 0.07 (2)，与 h(2) (d) 0.42 +/- 0.02 一致。通过双选实验计算出的产仔数和 6 周体重之间的实际遗传相关性 (r*(G(R))) 为 0.52 +/- 0.10 (1) 和 0.52 +/- 0.13 (2)，与基础群体估计值 r*( G(d) ) = 0.63 +/- 0.14 没有显着差异。拮抗指数选择系中的分歧（L（-）W（+）减去L（+）W（-））为0.21 +/- 0.01指数单位（I = 0.305 P（W）- 0.436 P（L），其中P（W）和P（L）分别是6周体重和产仔数的表型值。）。根据散度计算出的指数单位为 0.14 +/- 0.02 的 h(2) ( R) 与 0.14 +/- 0.04 的 h(2) (d) 一致。产仔数 (-0.19 +/- 0.07) 和 6 周体重 (0.46 +/- 0.10) 的差异符合预期方向。拮抗指数选择产生的产仔数预期差异约为二分之一，而 6 周体重差异仅略小于预期。已实现的遗传相关性表明，每窝产仔数、6周体重和指数单位均与3周体重、断奶后增重和阴道口体重呈正多效性，与阴道口日龄呈负多效性。在所选品系中，性别比例和健康的几个组成部分（从交配到分娩的天数、可育交配百分比和围产期存活率）没有显着变化。
INDIVIDUAL SELECTION BASED ON FEMALE PERFORMANCE ONLY WAS CONDUCTED IN FOUR LINES OF MICE: L(+) for increased litter size, W(+) for increased 6-week body weight, L(-)W(+) for a selection index aimed at decreasing litter size and increasing 6-week body weight and L(+)W(-) for a selection index aimed at increasing litter size and decreasing 6-week body weight. A fifth line (K) served as an unselected control. All litters were standardized to eight mice at one day of age. Expected heritability was based on twice the regression of offspring on dam (h(2) (d)), which contains additive genetic variance due to direct (sigma(2) (A(o) )) and maternal (sigma(2) (A(m) )) effects and their covariance (sigma(A(o)A(m) )). Responses and correlated responses were measured either deviated (method 1) or not deviated (method 2) from the control line. Realized heritabilities (h(2) (R)) for litter size were 0.19 +/- 0.04 (1) and 0.16 +/- 0.03 (2), which were similar to h( 2) (d) of 0.17 +/- 0.04. The h(2) ( R) for 6-week body weight of 0.55 +/- 0.07 (1) and 0.44 +/- 0.07 (2) agreed with h(2) (d) of 0.42 +/- 0.02. Realized genetic correlations (r*(G(R) )) between litter size and 6-week body weight calculated from the double-selection experiment were 0.52 +/- 0.10 (1) and 0.52 +/- 0.13 (2), which were not significantly different from the base population estimate of r*( G(d) ) = 0.63 +/- 0.14. Divergence (L(-)W( +) minus L(+)W(-)) in the antagonistic index selection lines was 0.21 +/- 0.01 index units (I = 0.305 P(W) - 0.436 P(L), where P( W) and P(L) are the phenotypic values for 6-week body weight and litter size, respectively.). The h(2) ( R) of index units of 0.14 +/- 0.02 calculated from divergence agreed with h(2) (d) of 0.14 +/- 0.04. Divergences in litter size (-0.19 +/- 0.07) and 6-week body weight (0.46 +/- 0.10) were in the expected direction. Antagonistic index selection yielded about one-half the expected divergence in litter size, while divergence in 6-week body weight was only slightly less than expected. Realized genetic correlations indicated that litter size, 6-week body weight and index units each showed positive pleiotropy with 3-week body weight, postweaning gain and weight at vaginal introitus and negative pleiotropy with age at vaginal introitus. Sex ratio and several components of fitness (days from joining to parturition, percent fertile matings and percent perinatal survival) did not change significantly in the selected lines.