Ecological Niche Differentiation and Distribution Dynamics Revealing Climate Change Responses in the Chinese Genus...

The genus Dysosma, a group of perennial herbaceous plants with significant medicinal value and a relatively narrow ecological niche, is potentially at risk due to the combined pressures of habitat degradation and climate change. As their habitats continue to degrade, all species of this genus have been included in the National Key Protected Wild Plants List (Category II). Investigating the impacts of climate change on the distribution of Dysosma resources is vital for their sustainable utilization. In this study, the potential distribution dynamics of seven Dysosma species under current and three future climate scenarios (SSP126, SSP245, SSP585) were quantified using 534 occurrence points and 25 environmental variables in a MaxEnt model, accompanied by the ecological niche overlap index (Schoener's D), dynamic metrics (relative change rate [RCR], change intensity [CI], stability index [SI], spatial displacement rate [SDR]), and centroid migration analysis. The results indicated that (1) areas of high habitat suitability were consistently concentrated in the mountainous and hilly regions of southwestern Guizhou, Chongqing, and Hubei, with the minimum temperature of the coldest month (Bio6) and the mean diurnal temperature range (Bio2) being identified as the primary driving factors. (2) The future suitable habitat areas remained highly stable overall (SI > 97.89%), though dynamic changes varied across scenarios. Under SSP126, only slight fluctuations were observed, with an average CI of approximately 3.78% and RCR ranging from -0.46% to 1.97%. Under the SSP245 scenario, suitable habitat areas showed a continuous, slight expansion (RCR = 0.45% to 1.54%), whereas under the high-emission SSP585 scenario, a typical "mid-term expansion-late-term contraction" pattern was observed, with RCR shifting from positive (1.32%, 1.44%) to negative (-0.92%). The SI reached its lowest value of 97.89% in the late term, and the spatial displacement rate increased, signaling a reorganization of the distribution pattern. (3) High ecological niche differentiation was observed within the genus, with the highest overlap index being only 0.562, and approximately one-third of species pairs exhibiting completely non-overlapping niches. (4) Dysosma tsayuensis, a niche-specialist species, exhibited a distribution that was highly dependent on the annual mean ultraviolet-B radiation (UVB, contribution rate 52.9%), displaying an adaptation strategy markedly different from that of conservative species. (5) Centroid analysis indicated that, although the overall centroid remained stable in Guizhou, the presence of niche-specialist species under the high-emission SSP585 scenario resulted in migration paths opposite to those observed under other scenarios. The findings reveal the potential vulnerability and differential response patterns of Dysosma species under rapid climate warming, thereby providing a scientific basis for targeted conservation, in situ and ex situ conservation strategies, and population restoration.