Hardy-Weinberg and allelic frequencies shifts suggest selection could act against melanin deposition
Inspecting deviations from HWE in the tawny owl population revealed punctual deviations from expected Hardy-Weinberg genotype frequencies:602-G/C , 2009Offspring : X2=5.20, p=0.02; 2018Adults+Offspring : X2=5.11, p=0.02; 2021Adults : X2=7, p=0.001; 3657-C/T , 2009Offspring : X2=6.25, p=0.01 (Table 3). Noticeably all reported deviations were due to an excess of homozygotes for the reference allele, combinations that yield the lowest probability of an individual being grey. Pairwise comparison of genotype frequencies between years also suggested the possibility of selection (Fig. S4), though we cannot discard a temporal effect since major deviations from the F-stat distribution obtained with 100 replicates and p-values < 0.01 related mostly to comparisons involving the 2009 cohort (Fig. S5).