生态式物种形成是新物种产生的重要方式。尽管已有大量研究探索其遗传机理，但对表达调控在生态式物种形成中的作用仍知之甚少。近日，中科院植物所葛颂研究组以野生稻为材料，在全基因组水平上探讨了表达调控进化在物种形成和适应性进化中的作用，相关成果发布于《分子生物学与进化》。

栽培稻近缘野生种Oryza rufipogon 和O. nivara 是近期分化的姊妹种，在形态、生境和生殖等方面存在显著差异，因此是研究物种形成的理想体系。研究人员通过对2个野生种3个生殖相关组织的转录组进行测序，发现约8%的基因在种间发生了显著的表达分化，并随机分布在基因组上。其中，约62%差异表达基因的表达模式受方向性选择的影响；相对于编码区，差异表达基因上游区域比非差异表达基因进化速度更快，说明基因调控在物种分化中起到了关键作用。进一步功能注释分析发现，差异表达基因显著集中在与生殖和逆境响应相关的基因上，这与2个野生种在表型和生态上的分化相一致。

该研究首次在全基因组水平上探讨了基因调控在植物物种形成中的作用，说明生态式物种形成伴随着广泛且具有适应性的表达分化，为进一步理解植物物种形成提供了重要证据。

该研究得到了国家自然科学基金委研究项目资助。（来源：中国科学报 萧杨）

Population genetic structure of Oryza rufipogon and Oryza nivara: implications for the origin of O. nivara

Abstract  Ecological speciation plays a primary role in driving species divergence and adaptation. Oryza rufipogon and Oryza nivara are two incipient species at the early stage of speciation with distinct differences in morphology, life history traits and habitat preference, and therefore provide a unique model for the study of ecological speciation. However, the population genetic structure of the ancestral O. rufipogon has been controversial despite substantial study, and the origin of the derivative O. nivara remains unclear. Here, based on sequences of 10 nuclear and two chloroplast loci from 26 wild populations across the entire geographic ranges of the two species, we conducted comprehensive analyses using population genetics, phylogeography and species distribution modelling (SDM) approaches. In addition to supporting the two previously reported major subdivisions, we detected four genetically distinct groups within O. rufipogon and found no correlation between the genetic groups and either species identity or geographical regions. The SDM clearly showed substantial change in the distribution range of O. rufipogon in history, demonstrating that the repeated extinction and colonization of local populations due to multiple glacial–interglacial cycles during the Quaternary was most likely the main factor shaping the confounding population genetic structure of O. rufipogon. Moreover, we found significant differences between the two species in climate preferences, suggestive of an important role for climatic factors in the adaptation, persistence and expansion of O. nivara. Finally, based on the genetic pattern and dynamics of the O. nivara populations, we hypothesize that O. nivara might have independently originated multiple times from different O. rufipogon populations.

原文链接：http://onlinelibrary.wiley.com/doi/10.1111/mec.13375/pdf