Divergence maintained by climatic selection despite recurrent gene flow: a case study of Castanopsis carlesii (Fagaceae)

Local adaptation to different environments has the potential to maintain divergence between populations despite recurrent gene flow and is an important driver for generating biological diversity. In this study, we investigate the role of adaptation in the maintenance of two parapatric varieties of a forest tree. We used sequence variation of chloroplastic DNA and restriction site-associated DNA to investigate the genetic structure of two varieties of Castanopsis carlesii in subtropical China and relate it to climatic variation. We used niche reconstruction methods to investigate niche differentiation between the two varieties and to estimate the past distribution of this species. A deep divergence was observed between the two varieties, but evidence of introgression and genetic admixture was detected in two phenotypically and geographically intermediate populations. Niche reconstruction suggests that the distribution of the two varieties was disjunct during periods of global cooling and...

尽管存在反复发生的基因流，针对不同环境的局部适应仍可维持种群间的遗传分化，同时也是驱动生物多样性形成的重要动力。本研究以中国亚热带地区的米槠（Castanopsis carlesii）两个邻域变种为研究对象，旨在探究适应作用在维持该变种存续过程中的角色。本研究利用叶绿体DNA（chloroplastic DNA）与限制性位点相关DNA（restriction site-associated DNA）的序列变异，解析该物种两个变种的遗传结构，并探讨其与气候变异的关联。此外，本研究采用生态位重建方法，探究两个变种间的生态位分化情况，并估测该物种的历史分布范围。研究结果显示，两个变种间存在显著的深度遗传分化，但在两个表型与地理均处于过渡状态的种群中，检测到了基因渐渗与遗传混合的信号。生态位重建结果表明，在全球冷期阶段，这两个变种的分布曾呈现间断分布格局，且……