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.