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

## TL;DR

This study predicts that climate change will cause an endangered orchid and its pollinator bee to shift their ranges in opposite directions, risking their coexistence and pollination.

## Contribution

The study is the first to use ensemble modeling to predict range shifts of an endangered orchid and its obligate pollinator under climate change.

## Key findings

- The orchid Changnienia amoena is projected to shift southeastward, while its pollinator Bombus trifasciatus shifts westward.
- Niche overlap between the orchid and its pollinator is expected to decrease, risking pollination efficiency.
- Annual precipitation and precipitation of the driest quarter are key environmental variables for each species.

## Abstract

Climate change threatens the survival of the endangered Chinese orchid Changnienia amoena, which is pollinated mainly by the bumblebee Bombus trifasciatus. Our study predicts where both species live now and where they will live in the future. As temperatures rise, the orchid’s suitable habitat may shrink and shift southeast, while its pollinator shows a westward shift in climatic suitability. This indicates the two species are likely to move in opposite directions, reducing their chances of meeting. Such a mismatch may lower pollination efficiency, thereby reducing the orchid’s distribution. These findings highlight the need for conservation plans that safeguard both the orchid and its obligate bee together, ensuring they continue to coexist.

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.