Mol Biol Evol. 2012 Jan;29(1):31-4. doi: 10.1093/molbev/msr218. Epub 2011 Sep 1.
Two recent high-profile studies offered empirical evidence for a "snowballing" accumulation of postzygotic incompatibilities in Drosophila and Solanum (tomatoes). Here we present a reanalysis of the Solanum data that is motivated by population genetic principles. Specifically, the high levels of intraspecific nucleotide polymorphism in wild tomato species and presumably large effective population size throughout the divergence history of this clade imply that ancestral polymorphism should be taken into account when evaluating sequence divergence between species. Based on our reanalyses of synonymous-site divergence between the four focal Solanum species and a wide range of ancestral polymorphism, we assessed under which conditions the reported accumulation of seed sterility factors supports the snowball effect. Our results highlight the pivotal impact of levels of ancestral polymorphism and alternate divergence values, and they illustrate that robust tests of the snowball effect in Solanum require genome-wide estimates of divergence.
最近的两项备受瞩目的研究为果蝇和茄属（西红柿）中合子后不相容性的“滚雪球”积累提供了经验证据。在这里，我们根据群体遗传原理重新分析了茄属的数据。具体来说，野生番茄物种中高度的种内核苷酸多态性以及该进化枝整个分化历史中可能存在的大有效种群大小意味着，在评估物种间序列分歧时，应该考虑到祖先多态性。基于我们对四个焦点茄属物种之间同义位点分歧和广泛的祖先多态性的重新分析，我们评估了报告的种子不育因子的积累在何种条件下支持滚雪球效应。我们的结果强调了祖先多态性和替代分歧值的关键影响，并说明在茄属中对滚雪球效应进行稳健测试需要全基因组的分歧估计。
