Custo individual, ontogenia e visita de femeas como moduladores da exibição de corte de machos em Corapipo gutturalis (Aves: Pipridae)

Abstract

The theory of sexual selection predicts adaptive evolution of secondary sexual characters that favor mating through male-male competition and female preference. As such, studying how these interactions shape sexual traits allows understanding their evolution through sexual selection. In order to be selected, traits must vary phenotypically among competing individuals, before getting stereotyped as a secondary sexual trait in a species. In fact, the variability of a secondary sexual trait may reflect, among other factors, variation in preference among individuals of the choosy sex, usually females. Courtship displays are elaborate behaviors commonly present in polygamous clades. Here we addressed the within population variation in courtship display behavior among male White-throated Manakins, Corapipo gutturalis, from Central Amazonia, where the species is commonly found displaying in fallen mossy logs in the understory of typical “terra-firme” upland forest. Then, we tested whether observed variation could be explained by variation in abiotic (environmental light) or biotic factors, either intrinsic male conditions (body mass and age) or the extrinsic social context of male displays (total number of males and female visits). Our results show extensive variation in courtship displays among males, both in total presence and display rates at logs as well as among the multiple elements from the behavioral repertoire described for the species. Among the factors that affected total exhibition rates and some of the behavioral elements were age, body mass and the frequency of female visitation to or nearby the display logs. These results support the idea of costly courtships displayed by males, particularly to males in definitive, “adult-like” plumages that incorporate more complex display elements not yet presented by males in pre-definitive, “juvenile-like” plumages. This ontogeny of male behavior suggests that practicing males may learn from more experienced males. Because female visits modulate male display rates that are costly, our results are compatible with the hotshot model proposed to explain lekking around more active males, which are selected by females.