Genetic rescue can facilitate the recovery of small and isolated populations suffering from inbreeding depression. Long-term effects are however complex, and examples spanning over multiple generations under natural conditions are scarce. The aim of this study was to test for long-term effects of natural genetic rescue in a small population of Scandinavian Arctic foxes (Vulpes lagopus). By combining a genetically verified pedigree covering almost 20 years with a long-term dataset on individual fitness (n = 837 individuals), we found no evidence for elevated fitness in immigrant F2 and F3 compared to native inbred foxes. Population inbreeding levels showed a fluctuating increasing trend and emergence of inbreeding within immigrant lineages shortly after immigration. Between 0–5 and 6–9 years post immigration, the average number of breeding adults decreased by almost 22% and the average proportion of immigrant ancestry rose from 14% to 27%. Y chromosome analysis revealed that 2 out of 3 native male lineages were lost from the gene pool, but all founders represented at the time of immigration were still contributing to the population at the end of the study period through female descendants. The results highlight the complexity of genetic rescue and suggest that beneficial effects can be brief. Continuous gene flow may be needed for small and threatened populations to recover and persist in a longer time perspective.

中文翻译：

---

北极狐（Vulpes lagopus）跨代遗传拯救的低持久性

基因拯救可以促进患有近亲繁殖抑郁症的小而孤立的种群的恢复。然而，长期影响是复杂的，在自然条件下跨越多代的例子很少。本研究的目的是测试自然基因拯救对一小群斯堪的纳维亚北极狐（Vulpes lagopus）的长期影响。通过将经过基因验证的近 20 年谱系与关于个体健康的长期数据集（n = 837 个体）相结合，我们发现没有证据表明移民 F2 和 F3 与本地近交狐狸相比健康状况有所提高。人口近亲交配水平呈波动增加趋势，移民后不久在移民血统内出现近亲交配。移民后 0-5 至 6-9 年，繁殖成虫的平均数量减少了近 22%，移民血统的平均比例从 14% 上升到 27%。Y 染色体分析显示，3 个本地男性血统中有 2 个从基因库中丢失，但在移民时代表的所有创始人在研究期结束时仍通过女性后代为人口做出贡献。结果突出了基因拯救的复杂性，并表明有益效果可能很短暂。小型和受威胁的种群可能需要持续的基因流来恢复并在更长的时间内持续存在。但在移民时代表的所有创始人在研究期结束时仍然通过女性后代为人口做出贡献。结果突出了基因拯救的复杂性，并表明有益效果可能很短暂。小型和受威胁的种群可能需要持续的基因流来恢复并在更长的时间内持续存在。但在移民时代表的所有创始人在研究期结束时仍然通过女性后代为人口做出贡献。结果突出了基因拯救的复杂性，并表明有益效果可能很短暂。小型和受威胁的种群可能需要持续的基因流来恢复并在更长的时间内持续存在。