INDEPENDENT OBSERVATIONS OF PHAEOMELANIC MALES OF THE VARIABLE SEEDEATER (SPOROPHILA CORVINA) WITH COMMENTS ABOUT ITS POTENTIAL FOR EVOLUTIONARY DIVERGENCE

Plumage coloration largely depends on the type and concentration of pigments present in feathers. Therefore, changes in pigment deposition may result in aberrant colorations, which, in turn, will likely interfere with the plumage color’s function (e.g., signaling, protection). Published records of aberrant plumage colors underestimate the type and frequency of these phenotypes, especially in the tropics. Here, we report five independent observations of phaeomelanic males of the Variable Seedeater (Sporophila corvina), in which typically white feathers were instead chestnut-red, likely due to the deposition of phaeomelanin. Our observations add to previous reports of aberrant melanin-based coloration in this species, suggesting that genomic region(s) influencing the expression of phaeomelanin are a biased target for mutations. Because mutations affecting the regulation of melanin deposition result in novel plumage phenotypes, we discuss aberrant phenotypes as an important source of variation fueling rapid divergence among populations of this avian clade