Spatially varying selection promotes variance in allele frequencies, increasing genetic differentiation between the demes of a metapopulation. For that reason, outliers in the genome‐wide distribution of summary statistics measuring genetic differentiation, such as F_ST, are often interpreted as evidence for alleles that contribute to local adaptation. However, theoretical studies have shown that in spatially structured populations the spread of beneficial mutations with spatially uniform fitness effects can also induce transient genetic differentiation. In recent years, numerous empirical studies have suggested that such species‐wide, or global, adaptation makes a substantial contribution to molecular evolution. In this perspective, we discuss how commonly such global adaptation may influence the genome‐wide distribution of F_ST and generate genetic differentiation patterns, which could be mistaken for local adaptation. To illustrate this, we use forward‐in‐time population genetic simulations assuming parameters for the rate and strength of beneficial mutations consistent with estimates from natural populations. We demonstrate that the spread of globally beneficial mutations in parapatric populations may frequently generate F_ST outliers, which could be misinterpreted as evidence for local adaptation. The spread of beneficial mutations causes selective sweeps at flanking sites, so in some cases, the effects of global versus local adaptation may be distinguished by examining patterns of nucleotide diversity within and between populations in addition to F_ST. However, when local adaptation has been only recently established, it may be much more difficult to distinguish from global adaptation, due to less accumulation of linkage disequilibrium at flanking sites. Through our discussion, we conclude that a large fraction of F_ST outliers that are presumed to arise from local adaptation may instead be due to global adaptation.

中文翻译：

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全球适应使针对局部适应的基因组扫描的解释变得复杂

空间上变化的选择促进了等位基因频率的变化，从而增加了种群分布之间的遗传差异。因此，测量基因分化的摘要统计数据在全基因组分布中的异常值，例如F _ST常常被解释为等位基因有助于局部适应的证据。然而，理论研究表明，在空间结构化种群中，有益突变的传播具有空间统一的适应性效应，也可以诱导瞬时遗传分化。近年来，大量的经验研究表明，这种物种范围的或全球的适应性对分子进化做出了重大贡献。从这个角度，我们讨论了这种全局适应如何可能影响F _ST的全基因组分布并生成可能被误认为是局部适应的遗传分化模式。为了说明这一点，我们使用实时种群遗传模拟，假设有益突变的速率和强度的参数与自然种群的估计值一致。我们证明，在全球范围内有益的突变在随父异居人口中的传播可能经常产生F _ST离群值，这可能被误解为当地适应的证据。有益突变的传播导致在侧翼位点的选择性扫描，因此在某些情况下，除了F _ST外，还可以通过检查种群内部和种群之间核苷酸多样性的模式来区分整体适应与局部适应的影响。。但是，仅在最近才建立局部适应性时，由于侧翼位点的连锁不平衡的积累较少，因此与全局适应性区分开来可能要困难得多。通过我们的讨论，我们得出结论，推测大部分由局部适应引起的F _ST异常值可能是由于整体适应引起的。