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Predicting the purebred-crossbred genetic correlation from the genetic variance components in the parental lines
Genetics Selection Evolution ( IF 4.1 ) Pub Date : 2021-02-04 , DOI: 10.1186/s12711-021-00601-w
Pascal Duenk 1 , Piter Bijma 1 , Yvonne C J Wientjes 1 , Mario P L Calus 1
Affiliation  

The genetic correlation between purebred and crossbred performance ( $${r}_{pc}$$ ) is an important parameter in pig and poultry breeding, because response to selection in crossbred performance depends on the value of $${r}_{pc}$$ when selection is based on purebred (PB) performance. The value of $${r}_{pc}$$ can be substantially lower than 1, which is partly due to differences in allele frequencies between parental lines when non-additive genetic effects are present. This relationship between $${r}_{pc}$$ and parental allele frequencies suggests that $${r}_{pc}$$ can be expressed as a function of genetic parameters for the trait in the parental lines. In this study, we derived expressions for $${r}_{pc}$$ based on genetic variances within, and the genetic covariance between parental lines. It is important to note that the variance components used in our expressions are not the components that are typically estimated in empirical data. The expressions were derived for a genetic model with additive and dominance effects (D), and additive and epistatic additive-by-additive effects (EAA). We validated our expressions using simulations of purebred parental lines and their crosses, where the parental lines were either selected or not. Finally, using these simulations, we investigated the value of $${r}_{pc}$$ for genetic models with both dominance and epistasis or with other types of epistasis, for which expressions could not be derived. Our simulations show that when non-additive effects are present, $${r}_{pc}$$ decreases with increasing differences in allele frequencies between the parental lines. Genetic models that involve dominance result in lower values of $${r}_{pc}$$ than genetic models that involve epistasis only. Using information of parental lines only, our expressions provide exact estimates of $${r}_{pc}$$ for models D and EAA, and accurate upper and lower bounds of $${r}_{pc}$$ for two other genetic models. This work lays the foundation to enable estimation of $${r}_{pc}$$ from information collected in PB parental lines only.

中文翻译:

从亲本系的遗传方差成分预测纯种杂种的遗传相关性

纯种和杂交性能($$ {r} _ {pc} $$)之间的遗传相关性是猪和家禽育种的重要参数,因为对杂交性能选择的响应取决于$$ {r} _ {基于选择的纯种(PB)性能。$$ {r} _ {pc} $$的值可能大大低于1,这部分是由于存在非累加遗传效应时亲本系之间的等位基因频率不同。$$ {r} _ {pc} $$和父母等位基因频率之间的这种关系表明,$$ {r} _ {pc} $$可以表示为亲代中性状的遗传参数的函数。在这项研究中,我们基于内部的遗传差异和亲本系之间的遗传协方差推导了$$ {r} _ {pc} $$的表达式。重要的是要注意,我们的表达式中使用的方差成分不是经验数据中通常估算的成分。这些表达式是针对具有加性和显性效应(D)以及加性和上位性逐加效应(EAA)的遗传模型得出的。我们通过模拟纯种的亲代系及其杂交来验证我们的表达,在这里可以选择或不选择亲代系。最后,使用这些模拟,我们调查了具有支配性和上位性或其他类型上位性的遗传模型的$$ {r} _ {pc} $$的价值,无法得出其表达。我们的模拟表明,当存在非累加效应时,$$ {r} _ {pc} $$会随着亲本系之间等位基因频率差异的增加而降低。与仅涉及上位性的遗传模型相比,涉及优势的遗传模型产生的$$ {r} _ {pc} $$值较低。仅使用父母行的信息,我们的表达式为模型D和EAA提供了$$ {r} _ {pc} $$的精确估计,为两个模型提供了$$ {r} _ {pc} $$的精确上下限其他遗传模型。这项工作为仅根据PB亲本行收集的信息估算$$ {r} _ {pc} $$奠定了基础。
更新日期:2021-02-04
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