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- Title
Sex-specific phenotypic integration: endocrine profiles, coloration, and behavior in fledgling boobies.
- Authors
Fargallo, Juan A.; Velando, Alberto; López-Rull, Isabel; Gañán, Natalia; Lifshitz, Natalia; Wakamatsu, Kazumasa; Torres, Roxana
- Abstract
Color expression in animals plays a key role in social environments as a mechanism to signal individual competitive capacities. This function is poorly known in juvenile stages. We show that shy-bold behavior in female, but not in male, fledglings of boobies was correlated with plumage coloration. Bolder individuals also had lower levels of circulating testosterone. Our study suggests that, as in adults, dull juvenile coloration may reflect competitive capacities that differ between sexes.The intensity of color expression in animals plays a key role in social environments as a mechanism to signal individual capacities in competitive contests. Selective pressures for resource competition differ at different stages of life and between sexes; therefore, coloration is expected to vary between juveniles and adults and between males and females. Exploring the covariance between coloration and other traits may help to understand the functional significance of color and the action of natural selection on multivariate phenotypes. Melanin-based plumage coloration was investigated in the masked booby Sula dactylatra in relation to melanin concentration, sex, hormone levels, and shy–bold behavior of chicks close to fledging. Darker brown boobies showed higher levels of both eumelanin and pheomelanin concentration and lower body mass. Males behaved bolder than females and showed on average 8% larger brown patches. Bolder females had smaller brown patches. Bolder individuals also had lower levels of circulating testosterone, but no differences in corticosterone levels were found. Stronger phenotypic integration was observed in females than males. Our study suggests that juvenile melanic coloration may reflect behavioral strategies by sex, endocrine profiles, and body mass indicating the convergence of different adaptive functions in a given phenotype, this being more evident in females. Direction of correlations differed from those predicted under the pleiotropic idea for color-related traits. These results suggest the possibility that juvenile plumage acts as a signaling system in a social context within the age class and suggest that plumage coloration may indicate different behavioral strategies.
- Subjects
BOOBIES (Birds); BIRD behavior; COLOR of birds; MELANINS; GENETIC pleiotropy; ANIMAL behavior
- Publication
Behavioral Ecology, 2014, Vol 25, Issue 1, p76
- ISSN
1045-2249
- Publication type
Article
- DOI
10.1093/beheco/art088