Evolutionary history of delayed plumage maturation in manakins (Aves: Pipridae)

Avian plumage maturation involves replacing feathers, via discrete molts, until reaching an iteratively-regenerated definitive plumage. In most birds, this process takes about one year. In the Neotropical lekking manakins (Pipridae), males of most species exhibit delayed plumage maturation (DPM), passing through drab predefinitive plumages for up to three years before reaching a sexually dichromatic, definitive plumage. We used a phylogenetic analysis to investigate the evolutionary history of DPM in manakins. Our unique dataset represents the developmental schedules of individual, colorful plumage patches. We found a single origin of one-year DPM, in which young males spend a year in a drab female plumage. Subsequently, there were three origins of two-year DPM, all of which featured the evolution of an intermediate plumage with colorful patches that distinguish young males from both females and older males. One species evolved three-year DPM by passing through ancestral plumage stages more slowly, and two lineages have secondarily evolved sexual monochromatism by paedomorphic retention of female plumage. By detailing this complex developmental evolutionary history, we show how the iterative regeneration of bird plumages creates multiple distinct levels of ontogenetic homologies and provides new insights into the macroevolution of social signals in young birds.