All-or-none形質のheritability推定法

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タイトル別名
  • A method of estimating heritability of all-or-none trait
  • All-or-none ケイシツ ノ heritability スイテイホウ

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説明

A method of estimating heritability of all-or-none trait is presented, which is based on two points:(1) In spite of the observed phenotype having only two alternative classes, the distribution of factor combination in the background of the observed phenotype may be assumed normal with a certain threshold, and (2) heritability may be estimated by comparing genetic gain with selection differential<BR>The selection differential on the scale of background phenotype (not observable) measured by its σ can be calculated from the observed percentage of individuals falling in one alternative class, using the well-known relationship l=z/p, where z is the ordinate of the normal curve at threshold and its value may easily be calculated from statistical table. The genetic gain measnred by σ may be computed by the formula<BR>ΔG=pri-1p1-pri-1p0<BR>where pri-1 reads “inverse probability integral” and p0 and p1 are the percentages observed in the parent and offspring populations, respectively. Knowing P, pri-1 p can be obtained from statistical tables (Figs. 1 and 2).<BR>Thus, sinceΔG=lh2, the formula<BR>h2=ΔG/l=pri-1p1-pri-1p0/z0/p0<BR>will be used to estimate heritability (Fig. 2).<BR>When both of the alternative classes can have their respective offspring populations, heritability may be estimated on the basis of information on the result of selection in both plus and minus directions.<BR>Hence<BR>h2=ΔG±/Δl±=pri-1p1I-pri-1p1II/Z0/p0(1-p0)<BR>where p1 I stands for the percentage in the population of offspring produced by the parents belonging to one alternative class and p1 II the percentage among offspring of parents classified in the other alternative (Fig. 3).<BR>Some incidental points and modifications of the method in application are discussed in the example of estimating heritability of twinning in sheep by this method.<BR>The heritability estimates of 0.28 and 0.24 by this method, which are equivalent to 0.13 and 0.11 when converted to those on the percentage scale, were obtained for the twinning in the first and the second lambings, respectively.

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  • 日本畜産学会報

    日本畜産学会報 28 (6), 362-366, 1958

    公益社団法人 日本畜産学会

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