极大似然法探测主基因的效能

The Power of Detecting Major Gene by Maximum Likelihood

采用 Monte Carlo模拟数据和极大似然法探测 F2 群体主基因 (MG)。研究了遗传力、显性比和样本容量三因素对探测 F2 群体 MG的影响。结果表明 :1)在主基因的被发现率上 ,三因素的影响力为 :遗传力 >样本容量 >显性比。当遗传力较小时 ,如 0 .3,即使样本容量高达 10 0 0 ,其发现能力也仅有 5 1.6 3% ;当遗传力大于 0 .5时 ,样本容量大于 30 0 ,MG的被发现率在 80 %以上。 2 )一般来说 ,一旦 MG被探测到 ,参数 d和 h估计的准确度均较高。并且 ,随着遗传力 h2b 和样本容量 c的增大 ,参数 d和 h估计的精度也随之提高。

The power of detecting major genes in different heritabilities, sample sizes and dominance ratio was investigated by the simulated data of F 2 population and maximum likelihood method. The results indicated that there were differences in the power of detecting major gene among the three affecting factors (heritability, sample size and dominance ratio). The order of effects of three factors on the power of detecting major gene is heritability>sample size>dominance ratio. The increase of both heritability and sample size can significantly enhance the power of detecting major gene, whereas the dominance has a little effect. Under the heritability being more than 0.5, the power of detecting major gene for sample size of 300 is over 80%. While heritability is 0.3, the power of detecting major gene for 1000 of sample size is only about 51.63%. Generally, once the major gene has been detected, the accuracy of estimates of additive effect ( d ) and dominant effect ( h ) was relatively high. Furthermore, as heritability and sample size increase, the accuracy of estimates of additive effect ( d ) and dominant effect ( h ) will increase.