New insight into the origin and evolution of the flora and fauna of Hainan Island, China----Xishuangbanna Tropical Botanical Garden,CAS

First Author:

Zhu, Hua

Abstract:

The origin of the biota of Hainan Island, China, remains a fundamental scientific problem. Comparative studies on the biota, geological tectonics, and paleomagnetism proposed that during the Eocene, Hainan Island connected Vietnam and Guangxi, and then moved to the southeast to reach its present location. This review mainly discusses its biota origin from molecular phylogeny and palaeobotanical research. The formation and evolution of the biological groups of Hainan Island were identified via research on their genomes, phylogeny, and molecular biogeography. This research showed that the genera and species that appeared and diverged early in their evolution (i.e., before the Miocene) can be explained by the land connection between Hainan Island, Vietnam, and Guangxi during the Eocene-Oligocene. According to Southeast Asian tectonic theory, in the Middle Miocene (at about 15 million years ago), Hainan Island had moved to its present position. The population and genetic divergence of species with late divergence times (after 15 Ma) can be reasonably explained by the close proximity (or land connection) between Hainan Island and the Leizhou Peninsula, enabling genetic communication between Hainan Island and the Chinese mainland, but have exceptional cases. Conclusions have been obtained through palaeobotanical studies, showing that in the Eocene-Oligocene period, southwest China and Hainan Island had subtropical vegetation and flora. However, the fossil group in southeast China (in Maoming, near present-day Hainan Island) in the Late Eocene indicated a tropical rainforest vegetation and flora. This suggests that in the Paleogene, Hainan Island may have been located near or on the southwest border of Guangxi and northern Vietnam, rather than in its present location. The floristic division of the flora of Hainan Island basically presents a northeast-southwest inclined distribution pattern. This pattern can be explained by the counterclockwise rotation of Hainan Island during its movement to the southeast as proposed by paleomagnetism research. The origin of Hainan Island as proposed by its geological tectonics and comparative research on its biota is further supported by evidence from molecular phylogeny, paleobotanical studies, and the distribution pattern of plant diversity in Hainan. In this paper, the time node (in the Miocene) of the evolution of its biota is also proposed, thereby providing a basis for the in-depth exploration of the origin and evolution of the biota of Hainan Island.

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Zhu, H

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2025

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SCIENCE CHINA-EARTH SCIENCES

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