BACKGROUND Crop wild relatives (CWRs) contain genetic diversity, representing an invaluable resource for crop improvement. Many of their traits have the potential to help crops to adapt to changing conditions that they experience due to climate change. An impressive global effort for the conservation of various CWR will facilitate their use in crop breeding for food security. The genus Brassica is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture. Brassica oleracea (or wild cabbage), a species native to southern and western Europe, has become established as an important human food crop plant because of its large reserves stored over the winter in its leaves. Brassica cretica Lam. (Bc) is a CWR in the brassica group and B. cretica subsp. nivea (Bcn) has been suggested as a separate subspecies. The species Bc has been proposed as a potential gene donor to brassica crops, including broccoli, cabbage, cauliflower, oilseed rape, etc. RESULTS: We sequenced genomes of four Bc individuals, including two Bcn and two Bc. Demographic analysis based on our whole-genome sequence data suggests that populations of Bc are not isolated. Classification of the Bc into distinct subspecies is not supported by the data. Using only the non-coding part of the data (thus, the parts of the genome that has evolved nearly neutrally), we find the gene flow between different Bc population is recent and its genomic diversity is high. CONCLUSIONS Despite predictions on the disruptive effect of gene flow in adaptation, when selection is not strong enough to prevent the loss of locally adapted alleles, studies show that gene flow can promote adaptation, that local adaptations can be maintained despite high gene flow, and that genetic architecture plays a fundamental role in the origin and maintenance of local adaptation with gene flow. Thus, in the genomic era it is important to link the selected demographic models with the underlying processes of genomic variation because, if this variation is largely selectively neutral, we cannot assume that a diverse population of crop wild relatives will necessarily exhibit the wide-ranging adaptive diversity required for further crop improvement.

中文翻译：

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作物野生近缘种Brassica cretica Lam的种内多样化。使用人口统计模型选择。

背景技术作物野生近缘种(CWR)含有遗传多样性，是作物改良的宝贵资源。它们的许多性状有可能帮助作物适应气候变化导致的条件变化。全球为保护各种 CWR 所做的令人印象深刻的努力将促进它们在作物育种中的使用，以确保粮食安全。芸苔属被列入《粮食和农业植物遗传资源国际条约》附件一。甘蓝（或野甘蓝）是一种原产于南欧和西欧的物种，由于其叶子中储存了大量的过冬物质，因此已成为重要的人类粮食作物。甘蓝 (Brassica cretica Lam)。(Bc) 是芸苔科和 B. cretica 亚种中的 CWR。妮维雅 (Bcn) 已被建议作为一个单独的亚种。Bc 物种已被提议作为芸苔属作物的潜在基因供体，包括西兰花、卷心菜、花椰菜、油菜等。 结果：我们对 4 个 Bc 个体（包括两个 Bcn 和两个 Bc）的基因组进行了测序。基于我们的全基因组序列数据的人口统计分析表明，Bc 群体并不是孤立的。数据不支持将 Bc 分类为不同的亚种。仅使用数据的非编码部分（因此，基因组中几乎中性进化的部分），我们发现不同 Bc 群体之间的基因流动是最近的，并且其基因组多样性很高。结论 尽管预测了基因流对适应的破坏性影响，但当选择不足以防止局部适应等位基因的丢失时，研究表明基因流可以促进适应，尽管基因流很高，但局部适应仍可以维持，并且遗传结构在基因流局部适应的起源和维持中发挥着重要作用。因此，在基因组时代，将选定的人口统计模型与基因组变异的基本过程联系起来非常重要，因为如果这种变异在很大程度上是选择性中性的，我们就不能假设农作物野生近缘种的多样化群体一定会表现出广泛的变异进一步改良作物所需的适应性多样性。