Hardy-Weinberg and allelic frequencies shifts suggest selection could act against melanin deposition
Inspecting deviations from HWE in the tawny owl population revealed deviations from expected Hardy-Weinberg genotype frequencies:602-G/C , 2009Offspring : HomRef = 22, Het = 2, HomAlt = 1, X2=5.20, p=0.02; 2018Adults+Offspring : HomRef = 15, Het = 4, HomAlt = 2, X2=5.11, p=0.02; 2021Adults : HomRef = 6; Het = 0; HomAlt = 1: X2=7, p=0.008; 3657-C/T , 2009Offspring : HomRef = 18, Het = 4, HomAlt = 3, 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 (approximately 50%). 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).