Tsun Fung Au1,2, Dr. Timothy Bonebrake1
1School of Biological Sciences, The University of Hong Kong, Hong Kong, China, 2Department of Geography, Indiana University, Bloomington, United States
A common response in butterflies to a warming climate is through distribution shifts. Hong Kong has documented records of several new butterfly species in recent decades, comprising tropical species and some of which have become successfully established. In this study, we examined possible drivers for the establishment of Euripus nyctelius by studying its thermal physiology and modeling current climate and future distributions projected by species distribution modelling (SDMs). We corroborated that Euripus nyctelius adults have a significantly higher critical thermal minimum than temperate relatives (in this case Hestina assimilis), suggesting a possible physiological constraint that may have been lifted with recent climatic warming. SDMs provide evidence that a shifting climate envelope may be changing the climate suitability for Euripus nyctelius but we also hypothesize that habitat changes in the region, potentially acting in concert with climate change, have led to the expansion of Euripus nyctelius. In sum, multiple drivers likely contributed to the establishment of this species and others in recent years in Hong Kong. Conclusive attribution of warming-driven impacts on these species however has been complicated by a lack of data. Tropical butterfly assemblages generally will require a significant advancement in efforts to monitor species and populations if we are to conclusively document climate-driven shifts in species distributions.
Tsun Fung (Tom) Au is now a PhD student at Department of Geography, Indiana University, studying species-specific tree growth responses to climate changes. The presentation at SOTM 2019 is about my undergraduate thesis on butterfly distribution shift.