Conclusions and future research on the evolution and maintenance of melanin-based colour polymorphism
Melanin-phenotypes represent phenotypic traits segregating in melanin-based colour polymorphic organism. In this study we demonstrate the colour phenotype in the tawny owl appears to be regulated by non-exonic polymorphisms in genes not traditionally associated with colour genes, perhaps like what has been reported for the barn owl (Luis M. San-Jose et al., 2017). This is not necessarily surprising, with quantitative differences in feather colour in the chicken also being regulated in such non-traditional genes (Fogelholm et al., 2020). Nevertheless, identifying genetic variation in regions responsible for environmental-dependent biological functions that co-vary with coloration is a step-forward to understand evolution and specially, the maintenance of intra-specific colour polymorphism. Potential follow-up work for this work would be to improve the screening density of the tawny owl genome while also adding information using transcriptomic and epigenetic sources to fully pin down the long theorized (genetic) linkage between colour producing genes and melanin-phenotypes (Fig. 3).