Genomic divergence and demographic history of Quercus aliena populations

Abstract

Background Quercus aliena is a major montane tree species of subtropical and temperate forests in China, with important ecological and economic value. In order to reveal the species’ population dynamics, genetic diversity, genetic structure, and association with mountain habitats during the evolutionary process, we re-sequenced the genomes of 72 Q. aliena individuals. Results The whole chloroplast and nuclear genomes were used for this study. Phylogenetic analysis using the chloroplast genome dataset supported four clades of Q. aliena, while the nuclear dataset supported three major clades. Sex-biased dispersal had a critical role in causing discordance between the chloroplast and nuclear genomes. Population structure analysis showed two groups in Q. aliena. The effective population size sharply declined 1 Mya, coinciding with the Poyang Glaciation in Eastern China. Using genotype–climate association analyses, we found a positive correlation between allele frequency variation in SNPs and temperature, suggesting the species has the capacity to adapt to changing temperatures. Conclusion Overall, this study illustrates the genetic divergence, genomic variation, and evolutionary processes behind the demographic history of Q. aliena.