J Syst Evol

• Research Article •    

Enhanced precipitation has driven the evolution of subtropical evergreen broad-leaved forests in eastern China since the early Miocene: Evidence from ring-cupped oaks

Dong-Mei Jin1†*, Quan Yuan1,2†, Xi-Ling Dai2, Gregor Kozlowski1,3,4, and Yi-Gang Song1*   

  1. 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 Department of Biology and Botanic Garden, University of Fribourg, Fribourg 1700, Switzerland;
    4 Natural History Museum Fribourg, Fribourg 1700, Switzerland
    These authors contributed equally to this study.
    *Authors for correspondence. Dong-Mei Jin. E-mail:jindongmei@csnbgsh.cn;Yi-Gang Song. E-mail:ygsong@cemps.ac.cn
  • Received:2023-02-02 Accepted:2023-08-16 Online:2023-10-15

Abstract: Subtropical evergreen broad-leaved forest (EBLF) is the predominant vegetation type in eastern China. However, the majority of the region it covers in eastern China was an arid area during the Paleogene. The temporal history and essential factors involved in the evolution of subtropical EBLFs in eastern China remain enigmatic. Here we report on the niche evolution of Quercus section Cyclobalanopsis, which appeared in south China and Japan during the Eocene and became a dominant component of subtropical EBLFs since the Miocene in eastern Asia, using integrative analysis of occurrences, climate data and a dated phylogeny of 35 species in Cyclobalanopsis. Species within clades Cyclobalanoides, Lamellosa, and Helferiana mainly exist in the Himalaya-Hengduan region, adapting to a plateau climate, while species within the other clades mainly live in eastern China under the control of the East Asian monsoon. Reconstructed history showed that significant divergence of climatic tolerance in Cyclobalanopsis began around 19 million years ago (Ma) in the early Miocene. Simultaneously, disparities in precipitation of wettest/warmest quarter and annual precipitation were markedly enhanced in Cyclobalanopsis, especially in the recent eastern clades. During the Miocene, the marked radiation of Cyclobalanopsis and many other dominant taxa of subtropical EBLFs strongly suggest the rapid formation and expansion of subtropical EBLFs in eastern China. Our research highlights that the intensification of the East Asian monsoon and subsequent occupation of new niches by the ancient clades already present in the south may have jointly promoted the formation of subtropical EBLFs in eastern China since the early Miocene.

Key words: climate, East Asian monsoon, Miocene, niche evolution, Quercus