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.