Hybridization occurs differentially across the genome in a balancing act between selection and migration. With the unprecedented resolution of contemporary sequencing technologies, selection and migration can now be effectively quantified such that researchers can identify genetic elements involved in introgression. Furthermore, genomic patterns can now be associated with ecologically relevant phenotypes, given availability of annotated reference genomes. We do so in North American box turtles (Terrapene) by deciphering how selection affects hybrid zones at the interface of species boundaries and identifying genetic regions potentially under selection that may relate to thermal adaptations. Such genes may impact physiological pathways involved in temperature‐dependent sex determination, immune system functioning and hypoxia tolerance. We contrasted these patterns across inter‐ and intraspecific hybrid zones that differ temporally and biogeographically. We demonstrate hybridization is broadly apparent in Terrapene, but with observed genomic cline patterns corresponding to species boundaries at loci potentially associated with thermal adaptation. These loci display signatures of directional introgression within intraspecific boundaries, despite a genome‐wide selective trend against intergrades. In contrast, outlier loci for interspecific comparisons exhibited evidence of being under selection against hybrids. Importantly, adaptations coinciding with species boundaries in Terrapene overlap with climatic boundaries and highlight the vulnerability of these terrestrial ectotherms to anthropogenic pressures.

中文翻译：

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北美盒龟（Terrapene spp。）接触区的渗入特征相反。

在选择和迁移之间的平衡作用中，杂交在整个基因组中发生差异。随着当代测序技术的空前解决，选择和迁移现在可以被有效地量化，以便研究人员可以鉴定出与基因渗入有关的遗传成分。此外，在有注释的参考基因组的情况下，基因组模式现在可以与生态相关的表型相关联。我们在北美箱龟（Terrapene），通过解释选择如何影响物种边界交界处的杂种区，并确定可能在选择中与热适应有关的遗传区域。这些基因可能会影响涉及温度依赖性性别确定，免疫系统功能和耐缺氧性的生理途径。我们在时间和生物地理上不同的种间和种内杂种区域对比了这些模式。我们证明杂交在Terrapene中很明显，但观察到的基因组cline模式对应于可能与热适应相关的位点处的物种边界。这些基因座在种内边界内显示方向性渗入的特征，尽管全基因组对种间有选择性。相反，用于种间比较的离群基因座显示出正在针对杂种进行选择的证据。重要的是，适应与物种边界重合箱龟重叠气候边界和突出这些地面外温动物以人为压力的脆弱性。