Pathogen‐mediated balancing selection is commonly considered to play an important role in the maintenance of genetic diversity, in particular in immune genes. However, the factors that may influence which immune genes are the targets of such selection are largely unknown. To address this, here we focus on Pattern Recognition Receptor (PRR) signalling pathways, which play a key role in innate immunity. We used whole‐genome resequencing data from a population of bank voles (Myodes glareolus ) to test for associations between balancing selection, pleiotropy and gene function in a set of 123 PRR signalling pathway genes. To investigate the effect of gene function, we compared genes encoding (a) receptors for microbial ligands versus downstream signalling proteins, and (b) receptors recognizing components of microbial cell walls, flagella and capsids versus receptors recognizing features of microbial nucleic acids. Analyses based on the nucleotide diversity of full coding sequences showed that balancing selection primarily targeted receptor genes with a low degree of pleiotropy. Moreover, genes encoding receptors recognizing components of microbial cell walls etc. were more important targets of balancing selection than receptors recognizing nucleic acids. Tests for localized signatures of balancing selection in coding and noncoding sequences showed that such signatures were mostly located in introns, and more evenly distributed among different functional categories of PRR pathway genes. The finding that signatures of balancing selection in full coding sequences primarily occur in receptor genes, in particular those encoding receptors for components of microbial cell walls etc., is consistent with the idea that coevolution between hosts and pathogens is an important cause of balancing selection on immune genes.

中文翻译：

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模式识别受体信号通路中的平衡选择与野生啮齿动物的基因功能和多效性有关。

通常认为病原体介导的平衡选择在维持遗传多样性，尤其是免疫基因方面起着重要作用。但是，可能影响哪些免疫基因是此类选择目标的因素在很大程度上尚不清楚。为了解决这个问题，在这里我们集中于模式识别受体（PRR）信号通路，其在先天免疫中起关键作用。我们使用了来自银行田鼠种群的全基因组重测序数据（Myodes glareolus），以测试一组123个PRR信号通路基因中平衡选择，多效性和基因功能之间的关联。为了研究基因功能的影响，我们比较了编码（a）微生物配体受体与下游信号蛋白的基因，以及（b）识别微生物细胞壁，鞭毛和衣壳成分的受体与识别微生物核酸特征的受体的基因。基于完整编码序列的核苷酸多样性的分析表明，平衡选择主要针对多效性程度低的受体基因。而且，编码识别微生物细胞壁成分等的受体的基因比识别核酸的受体更是平衡选择的重要目标。对编码和非编码序列中的平衡选择进行局部标记的测试表明，这种标记主要位于内含子中，并且在PRR途径基因的不同功能类别之间分布更均匀。完整编码序列中的平衡选择特征主要发生在受体基因中，特别是那些编码微生物细胞壁成分受体的受体基因中，这一发现与宿主和病原体之间的共同进化是平衡选择的重要原因有关。免疫基因。