The results of partial RDA indicated that pure environment was the most significant variable affecting the genetic variation of adaptive SNPs among three pure-effect portions; whereas pure demography was the most important pure-effect portions of all SNPs when controlling other factors (Fig. S5; Table 2). Forward selection also identified population structure as the most significant variable affecting the genetic variation of adaptive SNPs (Table S7). Environmental variables contributed to 80% of the explained variation in adaptive loci but 60% of the explained variation in all loci (Fig. S5). For adaptive loci, the three groups of variables explained a large proportion of the joint effects (45% of explained variation) (Fig. S5; Table 2). Another partial RDA that decomposed the contributions of climate, soil, and topography to the genetic variation in either the adaptive or all SNPs revealed that pure climate and soil variables explained significantly more of the genetic variation in adaptive SNPs than topography variables (Fig. S5). In agreement with the results of partial RDA, GF analysis demonstrated that demography was the top variable with the highest weighted R2 (Table S8; Fig S6), although geography explained a higher proportion of variation after summing the total weighted R2 (demography: 32%; geography: 47%).