The divergence of mean phenotypes under persistent directional selection
The divergence of mean phenotypes under persistent directional selection
复制标题
持续定向选择下平均表型的分歧
DOI：
10.1093/genetics/iyad091
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发表时间：
2023
期刊：
影响因子：
3.3
通讯作者：
Roze, ed., D.
中科院分区：
文献类型：
--
作者：
Devi, Archana;Speyer, Gil;Lynch, Michael;Roze, ed., D.
许多生物特征，特别是在细胞水平上，很可能处于跨系统发育谱系的持续定向选择之下。除非影响这些性状的所有突变都有足够大的影响，可以在所有物种中有效地选择，否则平均表型的梯度预计会由于随机遗传漂移的力量的差异而出现，在整个生命树上，随机遗传漂移的力量大约变化五个数量级。以前的理论工作检验了这种梯度可能出现的条件，重点放在影响性状的所有基因组位置都具有相同和持续的突变效应的简单情况。在这里，我们将这一理论扩展到包括更现实的生物情况，在这种情况下，对一个特征的突变影响在不同的核苷酸位置不同。对这种修改的追求导致了对单效应模型中通过链接效应产生选择性干扰的方式的半解析表达式的发展，然后将其扩展到更复杂的场景。发展的理论阐明了不同选择效应的突变相互干扰彼此固定的条件，并展示了不同地点之间的效应差异如何实质上改变和扩大平均表型和有效种群规模之间的预期比例关系。
Numerous organismal traits, particularly at the cellular level, are likely to be under persistent directional selection across phylogenetic lineages. Unless all mutations affecting such traits have large enough effects to be efficiently selected in all species, gradients in mean phenotypes are expected to arise as a consequence of differences in the power of random genetic drift, which varies by approximately five orders of magnitude across the Tree of Life. Prior theoretical work examining the conditions under which such gradients can arise focused on the simple situation in which all genomic sites affecting the trait have identical and constant mutational effects. Here, we extend this theory to incorporate the more biologically realistic situation in which mutational effects on a trait differ among nucleotide sites. Pursuit of such modifications leads to the development of semi-analytic expressions for the ways in which selective interference arises via linkage effects in single-effects models, which then extend to more complex scenarios. The theory developed clarifies the conditions under which mutations of different selective effects mutually interfere with each others’ fixation and shows how variance in effects among sites can substantially modify and extend the expected scaling relationships between mean phenotypes and effective population sizes.