Inbreeding refers to the fusion of related individuals' gametes, with self-fertilization (selfing) being an extreme form of inbreeding-involving gametes produced by the same individual. Selfing is expected to reduce heterozygosity by an average of 50% in one generation; however, little is known about the empirical variation on a genome level surrounding this figure and the factors that affect variation. We selfed genotypes of the cyclic parthenogen Daphnia magna and analysed whole genomes of mothers and selfed offspring, observing the predicted 50% heterozygosity reduction on average. We also saw substantial variation around this value and significant differences among mother-offspring pairs. Crossover analysis confirmed the known trend of recombination occurring more often towards the telomeres. This effect was shown, through simulations, to increase the variance of heterozygosity reduction compared to when a uniform distribution of crossovers was used. Similarly, we simulated inbred line production after several generations of selfing and we observed higher variance in achieved homozygosity when we consider a higher recombination rate towards the telomeres. Our empirical and simulation study highlights that the expected mean values of heterozygosity reduction show remarkable variation, which can help understand, for example, differences among inbred individuals.

中文翻译：

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循环孤雌生殖 Daphnia magna 中自交的基因组特征。

近亲繁殖是指相关个体配子的融合，自体受精（selfing）是同一个体产生的近亲繁殖配子的极端形式。自交有望在一代中平均减少 50% 的杂合度；然而，人们对围绕这个数字的基因组水平的经验变异以及影响变异的因素知之甚少。我们自交了环状孤雌生殖 Daphnia magna 的基因型，并分析了母亲和自交后代的全基因组，观察到预测的杂合性平均减少 50%。我们还看到围绕这个值的巨大变化以及母子对之间的显着差异。交叉分析证实了已知的端粒重组趋势。通过模拟显示了这种效果，与使用均匀分布交叉时相比，增加杂合度减少的方差。类似地，我们模拟了几代自交后的近交系生产，并且当我们考虑到端粒的更高重组率时，我们观察到实现的纯合性的更高方差。我们的经验和模拟研究强调，杂合度减少的预期平均值显示出显着的变化，这有助于理解，例如，近交个体之间的差异。