Contrasting Range Shifts of an Endangered Orchid Changnienia amoena and Its Obligate Pollinator Under Climate Change in China

Specialized plant–pollinator interactions are highly vulnerable to climate change, yet predicting their coupled responses remains challenging. The endangered orchid Changnienia amoena and its sole effective pollinator, Bombus trifasciatus, represent a great system to study such dynamics in China. However, existing research on their potential distributions shows substantial discrepancies due to methodological variations. We applied ensemble modeling in Biomod2, integrating multiple algorithms, to project the current and future (2041–2100, under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios) distributions of both species. Models were built using comprehensive occurrence records (123 for C. amoena, 43 for B. trifasciatus) and key environmental variables. Annual precipitation primarily affected the distribution of C. amoena, while precipitation of the driest quarter was key for B. trifasciatus. Under climate change, C. amoena is projected to contract slightly in suitable habitat and shift southeastward, whereas B. trifasciatus may expand in climatic suitability. Niche overlap between the two species is predicted to decrease, indicating a potential future spatial mismatch. This study is the first to predict the current suitable habitat and future changes in the endangered orchid and its pollinator through ensemble modeling. As a result, it highlights contrasting range shifts in this specialized mutualism, underscoring the risk of climate-driven interaction disruption. The findings provide a critical scientific basis for developing targeted conservation strategies for C. amoena that consider the spatial ecology of its obligate pollinator.