Variation in environmental variables
Through PCA, we analyzed the environmental information of the 314 extinction occurrences of Chinese pangolins out of the distribution range in 1970-2000 across China. After dimension reduction, Comp. 1 represented the precipitation of the coldest quarter (bio19, positive correlation), elevation and seasonality of precipitation (elevation and bio15, negative correlation). Comp. 2 represents the seasonality of temperature (bio4, positive correlation) and mean temperature of the driest quarter (bio9, negative correlation). Comp. 3 represents population counts (positive correlation) and grazing (negative correlation). The first two principal components accounted for 57.92% of the variance contribution rate (Fig. 4). Comp. 3 contributed 15.68%, and the first three contributed 73.6% of the variance. The PCA results indicated that climatic factors had a greater degree of variation than anthropic variables in extinction events.