Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria.
Mol Ecol. 2013 Apr;22(8):2106-17. doi: 10.1111/mec.12256. Epub 2013 Mar 4.
Strict maternal inheritance is considered a hallmark of animal mtDNA. Although recent reports suggest that paternal leakage occurs in a broad range of species, it is still considered an exceptionally rare event. To evaluate the impact of paternal leakage on the evolution of mtDNA, it is essential to reliably estimate the frequency of paternal leakage in natural populations. Using allele-specific real-time quantitative PCR (RT-qPCR), we show that heteroplasmy is common in natural populations with at least 14% of the individuals carrying multiple mitochondrial haplotypes. However, the average frequency of the minor mtDNA haplotype is low (0.8%), which suggests that this pervasive heteroplasmy has not been noticed before due to a lack of power in sequencing surveys. Based on the distribution of mtDNA haplotypes in the offspring of heteroplasmic mothers, we found no evidence for strong selection against one of the haplotypes. We estimated that the rate of paternal leakage is 6% and that at least 100 generations are required for complete sorting of mtDNA haplotypes. Despite the high proportion of heteroplasmic individuals in natural populations, we found no evidence for recombination between mtDNA molecules, suggesting that either recombination is rare or recombinant haplotypes are counter-selected. Our results indicate that evolutionary studies using mtDNA as a marker might be biased by paternal leakage in this species.
严格的母系遗传被认为是动物 mtDNA 的标志。尽管最近的报告表明，在广泛的物种中存在父系渗漏，但它仍然被认为是一种异常罕见的事件。为了评估父系渗漏对 mtDNA 进化的影响，必须可靠地估计自然种群中父系渗漏的频率。我们使用等位基因特异性实时定量 PCR（RT-qPCR）表明，在至少 14%的个体携带多种线粒体单倍型的自然种群中，异质性很常见。然而，次要 mtDNA 单倍型的平均频率很低（0.8%），这表明由于测序调查的能力不足，以前没有注意到这种普遍存在的异质性。根据异质母亲后代中 mtDNA 单倍型的分布，我们没有发现对一种单倍型存在强烈选择的证据。我们估计父系渗漏率为 6%，并且至少需要 100 代才能完全分拣 mtDNA 单倍型。尽管在自然种群中有很高比例的异质个体，但我们没有发现 mtDNA 分子之间存在重组的证据，这表明重组要么很少发生，要么重组单倍型被反向选择。我们的结果表明，在该物种中，使用 mtDNA 作为标记的进化研究可能会受到父系渗漏的影响。
