2.2.2. Bioclimatic and Topographic Data

Bioclimatic data used for the study included 19 bioclimatic variables with the spatial resolution of 30 arc-seconds (~1 km at the equator) representing current climatic conditions (average for 1950–2000) [45], obtained from the WorldClim dataset (https: //www.worldclim.org; accessed on 5 January 2022). Besides, three topographic variables (elevation, slope, and aspect) derived from digital elevation model (DEM) data downloaded from WorldClim were also used in the study. To improve the prediction accuracy by eliminating multicollinearity, we performed a Pearson correlation analysis on all environmental variables and retained the environmental factors with low correlation coefficients (|r| < 0.8) [58]. Among the environmental factors with high correlation coefficients (|r| > 0.8), we retained only one factor of the two variables [58]. Finally, a total of 11 environmental variables, including 8 bioclimatic variables and 3 topographic variables, were obtained to simulate the current potential habitat of *Meconopsis* (Table 1).


**Table 1.** Environmental variables for modelling the habitat suitability for *Meconopsis* species and four typical species.
