Realistic assessments of the impacts of global warming on population extinction risk are likely to require an integrated analysis of the roles of standing genetic variation, microhabitat thermal complexity, and the inter‐individual variation of heat tolerance due to both genetic differences and seasonal acclimatization effects. Here, we examine whether balancing selection and microhabitat temperature heterogeneity can interact to enhance the population persistence to thermal stress for the black mussel Septifer virgatus. We deployed biomimetic data loggers on the shore to measure the microhabitat‐specific thermal variation from June 2014 to April 2016. Thermal tolerance of specimens was indexed by measuring effects of temperature on heart rate. Genotyping of specimens was performed using double digestion restriction association RADSeq (ddRADseq). Our results show that inter‐individual variations in thermal tolerance correlate significantly with genetic differences at some specific gene loci, and that heterozygotes have higher thermal tolerances than homozygotes. The observed seasonal changes in genotype frequency suggest that these loci are under balancing selection. The ability of thermally resistant heterozygotes to survive in sun‐exposed microhabitats acts to balance the loss of homozygotes during summer and enable the persistence of genetic polymorphisms. Population persistence of the mussel is also facilitated by the micro‐scale variation in temperature, which provides refugia from thermal stress. Our results emphasize that inter‐individual variation in thermal tolerance and in microhabitat heterogeneity in temperature are important for the persistence of populations in rocky shore habitats.

中文翻译：

---

平衡选择和微生境温度变化对潮间黑贻贝Septifer virgatus耐热性的影响。

对全球变暖对种群灭绝风险的影响的现实评估可能需要对遗传变异，季节性和环境适应效应造成的遗传遗传变异，微生境热复杂性以及耐热性个体间差异的作用进行综合分析。在这里，我们检查平衡选择和微生境温度异质性是否可以相互作用以增强黑贻贝Septifer virgatus对热胁迫的种群持久性。。我们在海岸上部署了仿生数据记录仪，以测量2014年6月至2016年4月特定于微栖息地的热变化。通过测量温度对心率的影响来索引标本的热耐受性。使用双重消化限制关联RADSeq（ddRADseq）对标本进行基因分型。我们的结果表明，个体间的热耐受性差异与某些特定基因位点的遗传差异显着相关，并且杂合子的热耐受性高于纯合子。观察到的基因型频率的季节性变化表明这些基因座处于平衡选择之下。耐热杂合子在暴露于阳光下的微生境中生存的能力可平衡夏季纯合子的损失并确保遗传多态性的持久性。温度的微尺度变化也促进了贻贝的种群持久性，这使人们免受热应激的困扰。我们的研究结果强调，热耐受性的个体差异和温度中微生境的异质性对于多岩石海岸生境的种群持续存在至关重要。