4.3 The drivers of biodiversification in Hainan Island
As one of world-wide biodiversity hotspot, the richest biotic assembly were shaped in south-central mountains of Hainan Island. Apart from island isolation and monsoon climate factors, the phylogeographical patterns of multiple clades of Gesneriaceae were driven by Changhua River (Li et al., 2020; Ling et al., 2020a), which blocked gene flow between populations, and even facilitated significant distinctive climates on different sides (Xing et al., 2012). Thus, differ from uplift-driven diversification in the Hengduan Mountains (Xing & Ree, 2017), current plant diversity in South America under Andean orogeny (Luebert & Weigend, 2014), the high biodiversity and endemism may be caused by the positive isolation effect of Changhua and Wanglou Rivers.
However, Changhua River has potentially negative effects on landscape pattern and ecosystem integrity of Hainan Tropical Rainforest National Park by declining connection degree and increasing landscape fragmentation. The further habitat isolation and fragmentation caused by the expressway G9811 probably possess negative ecological effects in future. So, the ecological corridor should be constructed across Changhua River and expressway to lower ecological risk.