INRA, UMR 077, 42 rue George Morel, Beaucouzé, France.
Fungal Genet Biol. 2010 Jun;47(6):511-21. doi: 10.1016/j.fgb.2009.12.007. Epub 2010 Jan 7.
Patterns of multilocus DNA sequence variation within and between closely related taxa can provide insights into the history of divergence. Here, we report on DNA polymorphism and divergence at six nuclear loci in globally distributed samples of the ascomycete Venturia inaequalis, responsible for scab on apple, loquat, and pyracantha. Isolates from different hosts were differentiated but did not form diagnosable distinct phylogenetic species. Parameters of an Isolation-with-Migration model estimated from the data suggested that the large amount of variation shared among groups more likely resulted from recent splitting than from extensive genetic exchanges. Inferred levels of gene flow among groups were low and more concentrated toward recent times, and we identified two potentially recent one-off shifters from apple and pyracantha to loquat. These findings support a scenario of recent divergence in allopatry followed by introgression through secondary contact, with groups from loquat and pyracantha being the most recently differentiated.
在密切相关的分类群内和之间，多位点 DNA 序列变异的模式可以提供对分化历史的深入了解。在这里，我们报告了在全球分布的苹果黑星病菌（Venturia inaequalis）样本中六个核基因座的 DNA 多态性和分化，该病菌可引起苹果、枇杷和火棘的黑星病。来自不同宿主的分离株有分化，但未形成可诊断的不同的系统发育种。从数据中估计的隔离-迁移模型的参数表明，群体之间共享的大量变异更可能是由于最近的分裂而不是广泛的遗传交换造成的。推断的群体间基因流水平较低，且更集中在近期，我们还发现了两个来自苹果和火棘向枇杷的潜在的近期单一起始转移者。这些发现支持了一个最近在异地发生分歧，然后通过二次接触发生基因渗透的情景，来自枇杷和火棘的群体是最近分化的。
