Zhang Can-Yu, Cao Guan-Long, Hu Jian-Lin, Huang Pei-Han, Li Min, Su Ren-Ping, Fang Ou-Yan, Cai Xiang, Song Yi-Gang, Hu Guo-Xiong, Xie Kai-Qing, Li Lang, Zhou Shi-Shun, Tan Yun-Hong, Meng Hong-Hu, Li Jie
Yunnan Normal University, Kunming, 650500, Yunnan, China.
Plant Phylogenetics and Conservation Group, Center for Integrative Conservation, Yunnan Key Laboratory for Conservation of Tropical Rainforests and Asian Elephants, and Yunnan International Joint Laboratory for the Conservation and Utilization of Tropical Timber Tree Species, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, 650023, China.
Am J Bot. 2025 Aug;112(8):e70077. doi: 10.1002/ajb2.70077. Epub 2025 Jul 28.
The lateral displacement of the Indochina Peninsula, driven by the Indian-Asian plate collision, significantly altered the topography of the Indo-Burma ecoregion, affecting its climate and biological evolution. Despite the renowned biodiversity of the region, spatiotemporal patterns of evolution remain poorly understood.
We analyzed the Engelhardia spicata complex, which has a continuous distribution across Indo-Burma, based on a robust phylogenetic framework comprising 778 individuals from 80 populations, to elucidate spatiotemporal and paleogeological patterns of evolution. We used ancestral area reconstruction to reconstruct the historical biogeography of the species complex and to understand the broader evolutionary history of the Indo-Burma ecoregion.
An initial divergence within the E. spicata complex approximately 26.62 million years ago (Ma) separated a lineage in the Truong Son Mountain Range from one in the Hengduan Mountains and the Shan Plateau. The Shan Plateau and Hengduan Mountain lineages subsequently diverged around 23.03 Ma. These results highlight a three-tiered landform in the Indo-Burma ecoregion, characterized by high-elevation northern regions (Hengduan Mountains, Yunnan-Guizhou Plateau), intermediate-elevation central plateau (Shan Plateau), and low-elevation southern ranges (southern Truong Son Mountains).
Our findings support the tectonic hypothesis that crustal thickening and lateral extrusion of Indochina occurred simultaneously during the Late Oligocene, which led to the formation of the Indo-Burma ecoregion and highlights the biological significance of the resulting three-tiered landform (north-to-south altitudinal gradients) in these regions, providing novel insights into biogeographic patterns in Southeast Asia.
在印度 - 亚洲板块碰撞的驱动下，印度支那半岛的横向位移显著改变了印缅生态区的地形，影响了其气候和生物进化。尽管该地区拥有著名的生物多样性，但其时空演化模式仍知之甚少。
我们基于一个强大的系统发育框架，对在印缅地区连续分布的穗花黄杞复合体进行了分析，该框架包含来自80个种群的778个个体，以阐明其时空和古地质演化模式。我们使用祖先区域重建来重建该物种复合体的历史生物地理学，并了解印缅生态区更广泛的进化历史。
穗花黄杞复合体在约2662万年前首次分化，将长山山脉的一个谱系与横断山脉和掸邦高原的谱系分开。掸邦高原和横断山脉的谱系随后在约2303万年前分化。这些结果突出了印缅生态区的三层地形，其特征为高海拔的北部地区（横断山脉、云贵高原）、中等海拔的中部高原（掸邦高原）和低海拔的南部山脉（长山山脉南部）。
我们的研究结果支持了构造假说，即在渐新世晚期，印度支那的地壳增厚和横向挤压同时发生，这导致了印缅生态区的形成，并突出了由此产生的三层地形（从北到南的海拔梯度）在这些地区的生物学意义，为东南亚的生物地理模式提供了新的见解。
