Abstract

In correctly predicting that selection efficiency is positively correlated with the effective population size (N_e), the nearly neutral theory provides a coherent understanding of between-species variation in numerous genomic parameters, including heritable error (germline mutation) rates. Does the same theory also explain variation in phenotypic error rates and in abundance of error mitigation mechanisms? Translational read-through provides a model to investigate both issues as it is common, mostly nonadaptive, and has good proxy for rate (TAA being the least leaky stop codon) and potential error mitigation via “fail-safe” 3′ additional stop codons (ASCs). Prior theory of translational read-through has suggested that when population sizes are high, weak selection for local mitigation can be effective thus predicting a positive correlation between ASC enrichment and N_e. Contra to prediction, we find that ASC enrichment is not correlated with N_e. ASC enrichment, although highly phylogenetically patchy, is, however, more common both in unicellular species and in genes expressed in unicellular modes in multicellular species. By contrast, N_e does positively correlate with TAA enrichment. These results imply that local phenotypic error rates, not local mitigation rates, are consistent with a drift barrier/nearly neutral model.

中文翻译：

---

有效的种群规模预测了真核生物基因中的局部发生率，但不能局部缓解通读错误。

摘要

在正确预测选择效率与有效种群数量正相关（N _e），近乎中立的理论提供了对众多基因组参数中物种间变异的一致理解，包括遗传错误（种系突变）率。相同的理论是否也解释了表型错误率和错误缓解机制的多样性？翻译通读提供了一个模型来研究这两个问题，因为这是常见的，大多是非自适应的，并且具有良好的代理率（TAA是泄漏最少的终止密码子）和通过“故障安全”的3'附加终止密码子减轻了潜在的错误（ ASC）。先前的翻译通读理论表明，当人口规模较大时，局部缓解的弱选择可能有效，从而预测ASC富集与N _e之间呈正相关。与预测相反，我们发现ASC富集与N _e不相关。ASC富集虽然在系统发育上是高度斑驳的，但是在单细胞物种和多细胞物种中以单细胞模式表达的基因中都更为普遍。相反，N _e与TAA富集确实呈正相关。这些结果表明，局部表型错误率，而不是局部缓解率，与漂移势垒/接近中性模型一致。