Figure 1. Distribution of 24 chloroplast haplotypes of Pterocarya hupehensis.
Environmental factors and geographical barriers have historically shaped species' genetic structures, with the Sino-Japanese Floristic Region and Sichuan Basin being key study areas. Research has highlighted the role of the Qinghai-Tibet Plateau uplift and East Asian monsoon on biodiversity, yet the dynamics of species around the Sichuan Basin during the Miocene climate change, and how species characteristics and geographic barriers affected their genetic patterns remains underexplored. Most phylogeographic studies focus on chloroplast DNA, overlooking pollen-mediated gene flow in wind-pollinated species like the conservation-concerned Pterocarya hupehensis. This gap underscores the need for studies incorporating species-specific traits and gene flow mechanisms to enhance our understanding of phylogeographic patterns.
Forestry Research published online a paper entitled “Phylogeography of Pterocarya hupehensis reveals the evolutionary patterns of a Cenozoic relict tree around the Sichuan Basin” on 12 March 2024.
To investigate the phylogeographic history of Pterocarya hupehensis, researchers employed cpDNA sequence variation analysis, RAD-seq reads for nuclear DNA analysis, and ecological niche modeling. The cpDNA analysis revealed 91 polymorphisms and 24 haplotypes across 17 populations. The phylogenetic network resolved two main haplotype lineages (western and eastern lineages) and a divergence dating back to the middle Miocene (16.7 Mya). RAD-seq analysis of 122 samples identified 2,889 SNPs. Admixture analysis revealed that the genetic structure of P. hupehensis consisted of two lineages and detected genetic introgression in five populations. The researchers further analyzed the population demographic histories by ML tree, and found two strong signals with a high migration weight, indicating unidirectional gene flow in populations. Ecological niche modeling suggested that P. hupehensis population expansion occurred during the last interglacial period and suitable area for P. hupehensis in the western and southern Sichuan Basin were predicted to shrink under global warming. In addition, the cpDNA data revealed further divergence of the eastern lineage compared to nuclear DNA, suggesting that pollen flow is more influential than seed flow in shaping genetic structure.
In summary, this study underscores the importance of considering both seed and pollen-mediated gene flows in understanding the phylogeographic patterns of wind-pollinated relict species, highlighting the role of historical climate changes and geographical barriers in shaping current genetic distributions. The findings emphasize the need for conservation efforts focused on both exsitu and in situ strategies to protect this vulnerable species amidst environmental changes and human activities.
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References
DOI
Original Source URL
https://www.maxapress.com/article/doi/10.48130/forres-0024-0005
Authors
Zi-Jia Lu1,2#, Tian-Rui Wang1#, Si-Si Zheng1#, Hong-Hu Meng3,4, Jian-Guo Cao2*, Yi-Gang Song1,5,6*, & Gregor Kozlowski1,6,7
# These authors contributed equally: Zi-Jia Lu, Tian-Rui Wang, Si-Si Zheng
Affiliations
1.Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China
2.College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
3.Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223, China
4.Southeast Asia Biodiversity Research Institute, Chinese Academy of Sciences, Naypyidaw 05282, Myanmar
5.College of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou 311300, China
6.Department of Biology and Botanic Garden, University of Fribourg, Fribourg 1700, Switzerland
7.Natural History Museum Fribourg, Fribourg 1700, Switzerland
About Yi-Gang Song
Yi-Gang Song finished his PhD at the University of Fribourg (Department of Biology) and is now developing his research group at the Chenshan Plant Science Research Center of the Chinese Academy of Sciences in Shanghai, China. His main research interests are phylogeny, phylogeography and conservation biogeography of the genus Quercus (Fagaceae) and the genus Pterocarya (Juglandaceae). In the framework of the project Zelkova he is a tree expert and coordinator of the field work in China.
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