Phenotypic adaptation and genomic variation of Kandelia obovata associated with its northern introduction along southeastern coast of China

Jiaqi Zhang Sheng Ouyang Xingxing Cai Sheng Yang Qiuxia Chen Ji Yang Zhiping Song Wen-Ju Zhang Yuguo Wang Yan Zhu ^* Peng Nan

• Fudan University, Shanghai, China

Mangroves play a crucial role within coastal wetland ecosystems, with Kandelia obovata frequently utilized for introduction studies and cultivation research.Investigating the rapid adaptability of K. obovata across diverse environmental conditions offers valuable insights into how mangroves can effectively acclimate to global climate fluctuations. In this study, following a common garden experiment, we investigated variations in morphological traits between two distinct populations of K. obovata, Quanzhou (QZ) and Wenzhou (WZ), originating from the same introduction site Zhangzhou (ZZ). Our findings have uncovered divergent growth-defense trade-off mechanisms employed by these two populations when exposed to varying minimal temperatures in the coldest month within their respective habitats. Moreover, our observations have revealed discernible genetic divergence during the process of environmental acclimatization. Subsequent whole-genome re-sequencing analyses conducted across multiple populations along the southern coast of China have unveiled a significant decrease in genetic diversity within the northernmost population, suggesting that temperature plays a primary role in shaping genetic variability within the K. obovata species. Our study presents new evidence for the rapid adaptation of K. obovata and contributes to our understanding of environmental adaptation characteristics during its introduction to northern regions, which holds significant implications for the conservation and sustainable development of mangroves.