Some collections display increased proportions of dSNPs over all detected variants, high individual total mutation burden and lowered alpha-dfe values for adaptive mutations when accessions were stored over a long time (A). The expected and unexpected differences in panel A for dSNP proportion and total burden are shown in right blue and left orange boxes (but un-scaled for ease of illustration), respectively, while all the differences for alpha-dfe are expected and shown in left blue boxes. The stars within each box stand for the statistical significance (*P < 0.05; **P < 0.01; ***P < 0.001). These expectations were further supported with the increased count of unique dSNPs in the accessions with more storage years (B) in four collections. For example, the wheat collection shows the samples with 25 yr of storage or longer had 1,014 unique dSNPs, while the samples with 20 yr of storage or shorter had 789 unique dSNPs. Unique and shared dSNP counts in panel B are shown in top yellow and bottom blue bars, respectively.