Cumulative adaptive variation
We calculated polygenic scores for each individual to assess the cumulative contribution of each locus to the response to climatic conditions using the custom script in R [PK1] (Babin et al., 2017; Gagnaire & Gaggiotti, 2016). For each candidate adaptive locus, we first identified the favourable allele as the allele with a frequency that was positively associated with increasing values for a given climate variable (Hancock et al., 2011)⁠. Polygenic scores were calculated at the individual level by summing the total number of favoured alleles for a given climate variable, resulting in an independent score for each climate variable. To ensure loci independence, we used only one locus per RAD tag, but also performed the same analysis with loci obtained by all methods for comparison. To examine the effects of population structure on RDA results, we separately calculated polygenic scores for the outlier loci detected by RDA with and without correction for population structure (Table S7).