Projecting Suitability and Climate Vulnerability of Bhutanitis thaidina (Blanchard) (Lepidoptera: Papilionidae) with Conservation Implications.

Bhutanitis thaidina is an endemic, rare, and protected swallowtail in China. Deforestation, habitat fragmentation, illegal commercialised capture, and exploitation of larval food plants are believed to be the four major causes of population decline of B. thaidina in the recent decade. However, little attention was paid to the impact of climate change. This study used ecological niche factor analysis and species distribution model to analyse the current suitable areas for B. thaidina with BioClim variables as well as its future suitable areas under four future climate scenarios (represented by four Representative Concentration Pathways: RCP2.6, RCP4.5, RCP6.0, and RCP8.5). Statistical analysis was carried out to compare the possible area and altitude changes to the distribution of B. thaidina under changing climate. Our analyses showed that the suitable areas for B. thaidina are fragmented under the current climate, with four suitable centres in northwestern Yunnan, northeastern Yunnan and northwestern Guizhou, the western margin of Sichuan Basin, and Qinling mountains. Apart from further habitat fragmentation under climate change, slight range expansion (average 6.0-8.9%) was detected under the RCP2.6 and RCP4.5 scenarios, while more range contraction (average 1.3-26.9%) was detected under the RCP6.0 and RCP8.5 scenarios, with the two southern suitable centres suffering most. Also, a tendency of contraction (2,500-3,500 m) and upslope shift (~600 m) in suitable altitude range were detected. The findings of this study supported the climate-vulnerable hypothesis of B. thaidina, especially under future climate like the RCP6.0 and RCP8.5 scenarios, in terms of contraction in suitable areas and altitude ranges. Conservation priority should be given to northwestern Yunnan, northeastern Yunnan, and northwestern Guizhou to alleviate the stress of massive habitat loss and extinction. Refugial areas should be established in all four suitable centres to maintain genetic diversity of B. thaidina in China.