Abstract
Feathers comprise a series of evolutionary innovations but also harbor
colour, a key biological trait known to co-vary with life history or
complex traits. Those relationships are particularly true in
melanin-based pigmentation species due to known pleiotropic effects of
the melanocortin pathway – originating from melanin-associated
phenotypes. Here we explore the molecular basis of melanin coloration
and expected co-variation at the molecular level in the melanin-based,
colour polymorphic system of the tawny owl (Strix aluco ). An
extensive body of literature has revealed that grey and brown tawny owl
colour morphs differ in a series of life history and behavioral traits.
Thus, it is plausible to expect co-variation also at molecular level
between colour morphs. To investigate this possibility, we assembled the
first draft genome of the species against which we mapped ddRADseq reads
from 220 grey and 150 brown morphs - representing 10 years of pedigree
data from a population in Southern Finland - and explored genome-wide
associations with colour phenotype. Our results revealed putative
molecular signatures of cold adaptation strongly associated with the
grey phenotype, namely a non-synonymous substitution in MCHR1 ,
plus 2 substitutions in non-coding regions of FTCD andFAM135A whose genotype combinations obtained a predictive power
of up to 100% (predicting grey colour). These suggest a molecular basis
of cold environment adaptations predicted to be grey-morph specific. Our
results potentially reveal part of the molecular machinery of
melanin-associated phenotypes and provide novel insights towards
understanding the functional genomics of colour polymorphism in
melanin-based pigmented species.