Evidence for the independent evolution of sex-related signals in manakins.

In birds, colouration, dance, and song evolved into great elaboration. Males most frequently produce these signals to attract females, and their evolution is undoubtedly affected by natural and sexual selection. Song, dance, and colouration are attributes commonly involved in mate attraction and are generally considered targets of sexual selection. In many species, multiple signalling is present, often involving different signal modalities, but we still know very little about how they interact during the evolution of different species. Here, we analyzed manakin species, which present impressive displays, vibrant colouration, and simple songs, to determine if these multiple signals co-evolved or if they evolved independently, which in the latter case would mean that different signal types will convey different messages. Moreover, we attempted to determine which environmental and morphological factors were related to the evolution of each signal. We found that song, dance, and colour complexity evolved independently in manakins. The only exception was for dance complexity, which is negatively associated with plumage brilliance. We also found that dances were more complex in smaller species and habitats with less precipitation and appeared not to be related to the intensity of sexual selection. Differently, colour complexity evolution was only associated with sexual selection. Colour brightness was related to habitat cover and precipitation. Song complexity was unrelated to any of the predictors tested here. Our results indicate that colour, dance, and song evolved in an unrelated way, implying that they most likely have different signalling roles in the mating behaviour of these species, and they were revealed to be affected by different natural and sexual selection factors throughout their evolution.