Department of Zoology, Stockholm University, Stockholm, Sweden.
J Hered. 2021 May 24;112(3):276-285. doi: 10.1093/jhered/esab011.
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.
遗传拯救可以促进遭受近交衰退的小而孤立的种群的恢复。然而，长期效应是复杂的，并且在自然条件下跨越多个世代的例子很少。本研究的目的是在斯堪的纳维亚北极狐（Vulpes lagopus）的一个小种群中测试自然遗传拯救的长期效应。通过将一个遗传上经过验证的近 20 年的系谱与个体适应度的长期数据集（n = 837 个个体）相结合，我们没有发现 F2 和 F3 移民比本地近交狐狸具有更高的适应性的证据。种群近交水平呈波动上升趋势，移民后不久，移民谱系内就出现了近交。在移民后 0-5 年和 6-9 年期间，繁殖成年个体的平均数量减少了近 22%，移民祖先的平均比例从 14%上升到 27%。Y 染色体分析显示，2 个本地雄性谱系从基因库中消失，但在研究结束时，所有在移民时代表的创始人仍通过雌性后代为种群做出贡献。研究结果强调了遗传拯救的复杂性，并表明有益的影响可能是短暂的。对于小而受到威胁的种群，需要持续的基因流才能在更长的时间内恢复和持续存在。
