Li Zhi-Chao, Xu Chao-Qun, Zhao Wei, Nie Shuai, Bao Yu-Tao, Liu Hui, Xing Zhen, Mao Jian-Feng, Wang Xiao-Ru
State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, National Engineering Laboratory for Tree Breeding, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicines, Ministry of Education, Institute of Medicinal Plant Development, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100193, China.
Plant Divers. 2025 May 26;47(4):604-619. doi: 10.1016/j.pld.2025.05.009. eCollection 2025 Jul.
Hybridization is a driving force in ecological transitions and speciation, yet direct evidence linking it to adaptive differentiation in natural systems remains limited. This study evaluates the role of hybridization in the speciation of , a keystone forest species on the southeastern Tibetan Plateau. By creating artificial interspecific F1s and a long-term common garden experiment on the plateau, we provide assessments on 44 growth and physiological traits across four seasons, along with RNA sequencing. We found significant phenotypic divergence between and its putative parental species and , with demonstrating superior growth and dynamic balance between photosynthesis and photoprotection. The F1s closely resembled in most traits. Gene expression revealed 19%-10% of 34,000 examined genes as differentially expressed in and F1s relative to mid-parent expression values. Both additive (4%) and non-additive gene actions (5%-6% in F1s, 10%-12% in ) were common, while transgressive expression occurred more frequently in the stabilized natural hybrids, illustrating transcriptomic reprogramming brought by hybridization and further divergence by natural selection. We provide compelling evidence for hybridization-derived phenotypic divergence at both physiological and gene expression levels that could have contributed to the adaptation of to high plateau habitat where both parental species have low fitness. The altered physiology and gene expression in hybrids serve both as a substrate for novel ecological adaptation and as a mechanism for the initiation of reproductive isolation.
杂交是生态转变和物种形成的驱动力，但将其与自然系统中的适应性分化联系起来的直接证据仍然有限。本研究评估了杂交在青藏高原东南部一种关键森林物种——[物种名称缺失]物种形成中的作用。通过创造人工种间F1代，并在高原上进行长期的共同花园实验，我们对四个季节的44个生长和生理性状进行了评估，并进行了RNA测序。我们发现[物种名称缺失]与其假定的亲本物种[物种名称缺失]和[物种名称缺失]之间存在显著的表型差异，[物种名称缺失]在生长以及光合作用和光保护之间的动态平衡方面表现优异。F1代在大多数性状上与[物种名称缺失]非常相似。基因表达显示，在34000个检测基因中，有19%-10%在[物种名称缺失]和F1代中相对于中亲表达值存在差异表达。加性基因作用（4%）和非加性基因作用（F1代中为5%-6%，[物种名称缺失]中为10%-12%）都很常见，而超亲表达在稳定的自然杂交种中更频繁出现，这说明了杂交带来的转录组重编程以及自然选择导致的进一步分化。我们提供了令人信服的证据，证明在生理和基因表达水平上，杂交衍生的表型差异可能有助于[物种名称缺失]适应两个亲本物种适应性都较低的高高原栖息地。杂种中生理和基因表达的改变既作为新生态适应的基础，也作为生殖隔离起始的机制。
