Accumulation of detrimental mutations in small populations leads to inbreeding depression of fitness traits and a higher frequency of genetic defects, thus increasing risk of extinction. Our objective was to quantify the magnitude of inbreeding depression for survival at birth, in a closed rabbit population under long-term selection. We used an information theory-based approach and multi-model inference to estimate inbreeding depression and its purging with respect to the trait ‘kit survival at birth’ over a 25-year period in a closed population of Pannon White rabbits, by analysing 22,718 kindling records. Generalised linear mixed models based on the logit link function were applied, which take polygenic random effects into account. Our results indicated that inbreeding depression occurred during the period 1992–1997, based on significant estimates of the z-standardised classical inbreeding coefficient z.FL (CI95% − 0.12 to − 0.03) and of the new inbreeding coefficient of the litter z.FNEWL (CI95% − 0.13 to − 0.04) as well as a 59.2% reduction in contributing founders. Inbreeding depression disappeared during the periods 1997–2007 and 2007–2017. For the period 1992–1997, the best model resulted in a significantly negative standardised estimate of the new inbreeding coefficient of the litter and a significantly positive standardised estimate of Kalinowski’s ancestral inbreeding coefficient of the litter (CI95% 0.01 to 0.17), which indicated purging of detrimental load. Kindling season and parity had effects on survival at birth that differed across the three periods of 1992–1997, 1997–2007 and 2007–2017. Our results support the existence of inbreeding depression and its purging with respect to kit survival at birth in this Pannon White rabbit population. However, we were unable to exclude possible confounding from the effects of parity and potentially other environmental factors during the study period, thus our results need to be extended and confirmed in other populations.

中文翻译：

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在长期选择下，近亲凹陷可提高兔子种群出生时试剂盒的存活率。

小种群中有害突变的积累导致近亲适应性状的近交降低和遗传缺陷的发生频率增加，从而增加了灭绝的风险。我们的目标是在长期选择下的封闭兔子种群中，量化近亲衰退对出生时存活的影响。我们通过分析22,718种点燃动物，使用了基于信息论的方法和多模型推论来估计近交抑郁症及其在25年内针对“封闭繁殖”的Pannon White兔子在“出生时的成套件存活”性状的清除作用。记录。应用了基于对数链接函数的广义线性混合模型，该模型考虑了多基因随机效应。我们的结果表明，近亲衰退发生在1992-1997年期间，基于对z标准化经典近交系数z.FL（CI95％− 0.12至− 0.03）和凋落物z.FNEWL的新近交系数（CI95％− 0.13至− 0.04）和59.2的大量估计减少贡献创始人的百分比。近亲衰退在1997–2007年和2007–2017年期间消失。在1992年至1997年期间，最佳模型对凋落物的新近交系数进行了显着的负标准化估计，对Kalinowski的祖传近交系数进行了显着的正经标准化估计（CI95％0.01至0.17），表明存在清除有害负荷。在1992-1997年，1997-2007年和2007-2017年的三个时期中，点燃季节和均等对出生存活的影响有所不同。我们的结果支持了该Pannon White兔种群中近交性抑郁症的存在及其对试剂盒存活率的清除作用。但是，在研究期间，我们无法从均等和其他潜在环境因素的影响中排除可能的混淆，因此我们的结果需要在其他人群中进行扩展和确认。