Reduced fitness through genetic drift and inbreeding is a major threat to small and isolated populations. Although previous studies have generally used genetically verified pedigrees to document effects of inbreeding and gene flow, these often fail to capture the whole inbreeding history of the species. By assembling a draft arctic fox (Vulpes lagopus) genome and resequencing complete genomes of 23 additional foxes born before and after a well-documented immigration event in Scandinavia, we here look into the genomic consequences of inbreeding and genetic rescue. We found a difference in genome-wide diversity, with 18% higher heterozygosity and 81% lower F_ROH in immigrant F1 compared to native individuals. However, more distant descendants of immigrants (F2, F3) did not show the same pattern. We also found that foxes with lower inbreeding had higher probability to survive their first year of life. Our results demonstrate the important link between genetic variation and fitness as well as the transient nature of genetic rescue. Moreover, our results have implications in conservation biology as they demonstrate that inbreeding depression can effectively be detected in the wild by a genomic approach.

中文翻译：

---

濒危食肉动物近亲繁殖的基因组和健康后果

遗传漂变和近亲繁殖导致的适应性降低是对小而孤立的种群的主要威胁。尽管以前的研究通常使用经过基因验证的谱系来记录近亲繁殖和基因流动的影响，但这些研究往往无法捕捉到该物种的整个近亲繁殖历史。通过组装北极狐 ( Vulpes lagopus ) 基因组草图，并对在斯堪的纳维亚半岛发生有据可查的移民事件前后出生的另外 23 只狐狸的完整基因组进行重新测序，我们在这里研究了近亲繁殖和基因拯救的基因组后果。我们发现全基因组多样性存在差异，杂合度高 18%，F _ROH低 81%在移民 F1 中与本地人相比。然而，更远的移民后代（F2、F3）并没有表现出相同的模式。我们还发现，近亲繁殖程度较低的狐狸在出生后第一年存活的可能性更高。我们的结果证明了遗传变异和适应性以及遗传拯救的短暂性之间的重要联系。此外，我们的结果对保护生物学具有影响，因为它们表明可以通过基因组方法在野外有效检测近交衰退。