GWAS
Genome wide association mapping was conducted using an Accelerated Mixed Model (AMM) via the online web application GWA-Portal (Seren, 2018). Accession means estimated from REML were used for period, phase and RAE with no further transformation necessary. Genotype data used was from the full-sequence 1001 genomes dataset. Results were filtered for the top 10,000 -log10(P) values and then for hits with >5% MAF. Comparison to results from other models confirmed the major peaks and can be viewed in Supplementary Figure 6.