Influência das características da plumagem do macho no investimento e sucesso reprodutivo em Sporophila lineola

Abstract

In sexually dimorphic bird species, male’s plumage traits are used by females as criteria during mate choice. Female preference is related with plumage traits that is correlated with male quality. By choosing higher quality mates, females can gain direct and/or indirect benefits for their offspring. Once mate plumage traits can affect the offspring viability, it is expected that these traits also influence females' reproductive investment in a given breeding attempt. The differential allocation hypothesis predicts that females invest more in the breeding when paired with preferred males, since these provide better resources and/or genes. In contrast, the compensatory investment hypothesis predicts that females paired with non-preferred males may increase their investment to compensate the poor resources provided by them. We investigate these hypotheses in Lined Seedeaters Sporophila lineola, a socially monogamous songbird with a marked sexual dimorphism. Males have a black plumage with white patches evident on the head, malar region, wing and rump (black-and-white males), while females are brownish. Interestingly, cases of males breeding in female-like plumage (brownish males) are reported. Moreover, given that some aspects of mate choice and the process underlying this phenotypic variation in male’s breeding plumage coloration remain unclear for this species, we also gathered data to improve the knowledge about these topics. This work used breeding data from a seven-year long study of color-banded population in southeastern Brazil. In chapter 1, we describe male displays that suggest nesting sites to females, which could be a sexually selected behaviour in Lined Seedeaters. In chapter 2, we describe the delayed plumage maturation in this species, and we show that males in female-like plumage are formative individuals in their first breeding season. In chapter 3, we report that investment on eggs and offspring survival can be attributed to male plumage colour, and females mated with brownish males have a higher reproductive investment. In the chapter 4, our findings show that coronal stripe and malar patch of black-and-white males influence the female reproductive investment, with females laying smaller eggs when mated with males with larger coronal stripes and malar patches. In summary, we show that plumage traits may be important for revealing the quality differences among males in Lined Seedeaters, consequently affecting female’s reproductive investment and pair breeding performance.