Macro-evolutionary dynamics dominated by dispersal promote the formation of regional biodiversity hotspot-insights from hawkmoths (Lepidoptera: Sphingidae) in South China

"Aim: Rapid loss in global insect diversity has generated substantial public worry due to their critical ecological roles. However, there is controversy about the effectiveness of the global-scale hotspots in guiding the conservation of diversity at the regional scale. Even worse, little is known about the knowledge of insect distributional dynamics in many understudied regions, such as East and Southeast Asia. Here, to guide for setting regional-scale conservation priorities for insect diversity, we explore hawkmoths (Lepidoptera: Sphingidae) for their distributional dynamics and identify regional hotspots requiring protection.
Location: South China (including Guangdong, Guangxi, Hainan, Hong Kong and Macau) and northern Vietnam (17°~26.5° N, 102°~117.5° E).
Methods: Species distribution models were generated for 194 hawkmoth species based on 3597 occurrence records to predict their distributions. We calculated the spatial patterns of taxonomic and phylogenetic diversity and identified regional hotspots. Furthermore, the potential assembly mechanisms underlying insect diversity were explored by analysing the rates of speciation, extinction and dispersal between phyloregions.
Results: (a) The coastal regions of South China and northern Vietnam represent a regional hotspot of hawkmoths in East and Southeast Asia, with significantly higher α-diversity than that in inland regions. (b) Dispersal played a more important role than local speciation and extinction in the formation of regional hawkmoth hotspots.
Main Conclusions: In this study, the ‘Out-of-the-tropics model’ can explain the formation of the hawkmoth regional hotspots and the enhanced version of the ‘Pure dispersal model’ can explain the formation of the hotspots in Hainan Island. Compared with the local speciation and extinction, dispersal is the main driving factor that promoted the formation of the regional biodiversity hotspot of hawkmoths in South China. The case of Hainan Island suggests that protection within hotspots needs to account for specific regional macro-evolutionary dynamics rather than indiscriminate coverage of identified hotspots."