BACKGROUND Recombination is a fundamental part of mammalian meiosis that leads to the exchange of large segments of DNA between homologous chromosomes and is therefore an important driver of genetic diversity in populations. In breeding populations, understanding recombination is of particular interest because it can break up unfavourable linkage phases between alleles and produce novel combinations of alleles that could be exploited in selection. In this study, we used dense single nucleotide polymorphism (SNP) genotype data and pedigree information to analyse individual and sex-specific variation and genetic architecture of recombination rates within and between five commercially selected pig breeds. RESULTS In agreement with previous studies, recombination rates were higher in females than in males for all breeds and for all chromosomes, except 1 and 13, for which male rates were slightly higher. Total recombination rate differed between breeds but the pattern of recombination along the chromosomes was well conserved across breeds for the same sex. The autosomal linkage maps spanned a total length of 1731 to 1887 cM for males and of 2231 to 2515 cM for females. Estimates of heritability for individual autosomal crossover count ranged from 0.04 to 0.07 for males and from 0.08 to 0.11 for females. Fourteen genomic regions were found to be associated with individual autosomal crossover count. Of these, four were close to or within candidate genes that have previously been associated with individual recombination rates in pigs and other mammals, namely RNF212, SYCP2 and MSH4. Two of the identified regions included the PRDM7 and MEI1 genes, which are known to be involved in meiosis but have not been previously associated with variation in individual recombination rates. CONCLUSIONS This study shows that genetic variation in autosomal recombination rate persists in domesticated species under strong selection, with differences between closely-related breeds and marked differences between the sexes. Our findings support results from other studies, i.e., that individual crossover counts are associated with the RNF212, SYCP2 and MSH4 genes in pig. In addition, we have found two novel candidate genes associated with the trait, namely PRDM7 and MEI1.

中文翻译：

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猪的重组率因品种、性别和个体而异，并且与 RNF212、SYCP2、PRDM7、MEI1 和 MSH4 基因座相关。

背景重组是哺乳动物减数分裂的基本部分，它导致同源染色体之间的大段DNA交换，因此是种群遗传多样性的重要驱动因素。在育种群体中，了解重组具有特别重要的意义，因为它可以打破等位基因之间不利的连锁阶段，并产生可用于选择的新型等位基因组合。在这项研究中，我们使用密集的单核苷酸多态性 (SNP) 基因型数据和谱系信息来分析五个商业选择的猪品种内和之间的个体和性别特异性变异以及重组率的遗传结构。结果 与之前的研究一致，所有品种和所有染色体的雌性重组率都高于雄性，除了 1 和 13，男性比率略高。品种之间的总重组率不同，但沿染色体的重组模式在同性品种之间得到了很好的保护。男性常染色体连锁图谱的总长度为 1731 至 1887 厘米，女性为 2231 至 2515 厘米。个体常染色体交叉计数的遗传力估计值男性为 0.04 至 0.07，女性为 0.08 至 0.11。发现 14 个基因组区域与个体常染色体交叉计数相关。其中，有四个接近或位于先前与猪和其他哺乳动物的个体重组率相关的候选基因中，即 RNF212、SYCP2 和 MSH4。两个已确定的区域包括 PRDM7 和 MEI1 基因，已知与减数分裂有关，但以前与个体重组率的变化无关。结论 本研究表明，在强选择下，驯化物种中常染色体重组率的遗传变异持续存在，近亲品种之间存在差异，两性之间存在显着差异。我们的研究结果支持其他研究的结果，即个体交叉计数与猪的 RNF212、SYCP2 和 MSH4 基因相关。此外，我们还发现了两个与该性状相关的新候选基因，即PRDM7和MEI1。密切相关的品种之间存在差异，两性之间存在显着差异。我们的研究结果支持其他研究的结果，即个体交叉计数与猪的 RNF212、SYCP2 和 MSH4 基因相关。此外，我们还发现了两个与该性状相关的新候选基因，即PRDM7和MEI1。密切相关的品种之间存在差异，两性之间存在显着差异。我们的研究结果支持其他研究的结果，即个体交叉计数与猪的 RNF212、SYCP2 和 MSH4 基因相关。此外，我们还发现了两个与该性状相关的新候选基因，即PRDM7和MEI1。