Data from: Inbreeding depression in a critically endangered carnivore

Harmful effects arising from matings between relatives (inbreeding) is a long-standing observation that is well founded in theory. Empirical evidence for inbreeding depression in natural populations is however rare because of the challenges of assembling pedigrees supplemented with fitness traits. We examined the occurrence of inbreeding and subsequent inbreeding depression using a unique data set containing a genetically verified pedigree with individual fitness traits for a critically endangered arctic fox (Vulpes lagopus) population. The study covered nine years and was comprised of 33 litters with a total of 205 individuals. We recorded that the present population was founded by only five individuals and over the study period, the population exhibited a tenfold increase in average inbreeding coefficient with a final level corresponding to half-sib matings. Inbreeding mainly occurred between cousins, but we also observed two cases of full-sib matings. The pedigree data demonstrated clear evidence of inbreeding depression on traditional fitness traits where inbred individuals displayed reduced survival and reproduction. Fitness traits were however differently affected over the lemming cycle. Inbred individuals born at low-quality years displayed reduced 1st year survival, while inbred individuals born at high-quality years were less likely to reproduce. The documentation of inbreeding depression in fundamental fitness traits suggest that inbreeding depression may limit population recovery. Introducing new genetic material to promote a genetic rescue effect may be necessary for population long-term persistence.近亲交配（inbreeding）所引发的有害效应是一个长期被观测到且理论依据充分的现象。然而，由于难以构建结合适合度性状（fitness traits）的系谱（pedigree）记录，自然种群中近交衰退（inbreeding depression）的实证证据较为匮乏。本研究借助一套独特的数据集，对极危种群北极狐（Vulpes lagopus）的近交发生情况及后续近交衰退展开了探究，该数据集包含经遗传验证的系谱记录与个体适合度性状数据。本研究历时九年，涵盖33窝幼崽，共计205只个体。研究记录显示，该种群仅由5只个体奠基组建；在研究周期内，种群的平均近交系数提升了十倍，最终水平等同于半同胞交配（half-sib matings）后的近交系数。近交主要发生于堂（表）亲个体之间，研究同时观测到两例全同胞交配（full-sib matings）事件。系谱数据清晰证实，近交衰退对传统适合度性状存在显著影响：近交个体的存活能力与繁殖能力均出现下降。不过，适合度性状所受影响会随旅鼠周期（lemming cycle）发生动态变化。在环境质量较差的年份出生的近交个体，其第一年存活率有所降低；而在环境质量较佳的年份出生的近交个体，则更难完成繁殖。核心适合度性状存在近交衰退的记录表明，近交衰退可能会限制种群的恢复进程。为实现种群的长期存续，或许有必要引入新的遗传物质以发挥遗传拯救效应（genetic rescue effect）。