Research Geneticist, USDA-ARS, Room 354, Throckmorton Hall, Kansas State University, 66506, Manhattan, KS, USA.
Theor Appl Genet. 1984 May;68(1-2):35-41. doi: 10.1007/BF00252308.
The genetic variance among F2-derived lines of backcrosses (BCgF2-derived lines) depends on the backcross generation (g), the number of F1 plants crossed and selfed in generations 1 through g, and the number of BCgF2-derived lines evaluated. Additive genetic variance decreases linearly with backcrossing when one BCF1 plant per generation is crossed and selfed. The relationship is curvilinear if more than one BCF1 plant is used; as the number of BCF1 plants increases, additive genetic variance among BC1F2-derived lines approaches that among BC0F2-derived lines. The effect of population size on genetic variance is due both to fixation of alleles in previous generations and to sampling of genotypes in the population being evaluated. Dominance and repulsion linkage can cause small increases in genetic variance from BC0 to BC1.
回交后代（BCgF2 衍生系）的遗传方差取决于回交世代（g）、F1 代在世代 1 到 g 中杂交和自交的数量，以及评估的 BCgF2 衍生系的数量。当每代杂交和自交一个 BCF1 植物时，加性遗传方差呈线性下降。如果使用多个 BCF1 植物，则关系呈曲线形；随着 BCF1 植物数量的增加，BC1F2 衍生系之间的加性遗传方差接近 BC0F2 衍生系之间的加性遗传方差。群体大小对遗传方差的影响既源于前几代等位基因的固定，也源于被评估群体中基因型的抽样。显性和排斥连锁可以导致从 BC0 到 BC1 的遗传方差的微小增加。
