Climate-Driven Expansion and Spatial Reconfiguration of Ottelia acuminata Under Future Scenarios

Climate-based suitable habitats were projected for the endangered submerged macrophyte Ottelia acuminata under current and future climates (2050s–2090s) across three Shared Socioeconomic Pathways (SSPs: SSP126, SSP245, and SSP585, corresponding to SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively) using the Maximum Entropy (MaxEnt) model with 126 occurrence points and eight environmental variables. The four dominant climatic factors were Precipitation of the Driest Quarter (34.7%), Isothermality (24.2%), Temperature Annual Range (17.9%), and Mean Temperature of the Coldest Quarter (11.7%). Under the current climate, the total suitable area is 121.07 × 104 km2, mainly in northern and eastern Yunnan. Under future scenarios, the total suitable area expands, peaking at +17.1% under SSP245 in the 2070s, but undergoes substantial internal reconfiguration: moderately suitable areas increase by 95.2% under SSP585 in the 2090s while low-suitability areas decline sharply, and core-habitat loss is greatest under SSP126. The distribution centroid consistently shifts westward (maximum 83.3 km), driven by newly suitable areas in the west and north. We propose a zonal conservation strategy grounded in these climate-envelope projections, while emphasizing that additional data on hydrology, water quality, and dispersal are required to translate these results into operational conservation actions. These findings provide a macroecological basis for informing climate-adaptive conservation of O. acuminata.