Transcriptomics of Heliosperma pusillum ecotypes

We quantify the degree of gene expression and functional parallelism across replicated ecotype formation in Heliosperma pusillum (Caryophyllaceae) and gain insights into the architecture of adaptive traits. Population structure analyses and demographic modelling confirm the previously formulated hypothesis of parallel polytopic divergence of montane and alpine ecotypes. We detect a large proportion of differentially expressed genes (DEGs) underlying adaptation of each replicate ecotype pair, with a strikingly low amount of shared DEGs across pairs. Functional enrichment of DEGs reveals that the traits affected by divergent gene expression are the same across ecotype pairs, in strong contrast to the non-shared genetic basis. The remarkable redundancy of differential gene expression indicates that diverged adaptive traits are highly polygenic. We conclude that polygenic traits appear key to opening multiple routes for adaptation, widening the adaptive potential of organisms.

本研究量化了纤细白鼓钉（Heliosperma pusillum，石竹科Caryophyllaceae）多个独立演化生态型形成过程中的基因表达水平与功能平行性，并深入解析了适应性性状的调控架构。通过种群结构分析与种群统计建模，我们验证了此前提出的山地与高山生态型平行多基因分化假说。研究发现，每一组重复生态型对的适应性演化均由大量差异表达基因（differentially expressed genes, DEGs）介导，但不同生态型对间共享的DEGs比例极低。对DEGs的功能富集分析显示，受差异表达调控的适应性性状在所有生态型对中均保持一致，这与非共享的遗传基础形成强烈反差。差异基因表达的显著冗余性表明，分化形成的适应性性状属于高度多基因调控的复杂性状。综上，我们认为多基因调控性状是解锁多条适应性演化路径的核心要素，能够有效拓宽生物的适应性演化潜力。