Examinando por Autor "Fargallo, Juan Antonio"

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Eggshell pigmentation has no evident effects on offspring viability in common kestrels
(Springer, 2014) Fargallo, Juan Antonio; López-Rull, Isabel; Miksik, Ivan; Eckhardt, Adam; Peralta-Sanchez, Juan Manuel
Infectious diseases and parasitism are major environmental forces decreasing fitness, and thus individual strategies aimed at preventing pathogen infections, either in an individual or their offspring, should be favoured by natural selection. The mineral fraction and some organic compounds in the shells of bird eggs are considered physical and chemical barriers against pathogen penetration to the embryo. However, eggshell pigment deposition has only recently been considered as a mechanism to resist pathogen penetration into the egg. By wiping the eggshell surface, the amount of pigment and some cuticle proteins were experimentally manipulated for the first time in nature. The effects on egg hatchability and offspring viability measured as nestling condition, immunocompetence and probability of recruitment were investigated in the common kestrel Falco tinnunculus. Protoporphyrin IX and biliverdin IXa to a lesser extent were the only identified pigments. The concentration of protoporphyrin IX and cuticle proteins were significantly reduced in the wiped with respect to the control treatment. Our study shows no evidence of a detrimental effect of the reduction of eggshell pigments on egg hatchability, mortality of the chicks during the nesting period, nestling body condition, nestling local immune response to PHA antigen or probability of recruitment. Further research will be necessary to elucidate the direct role of protoporphyrins and other pigments in egg bacterial infection.
Plumage coloration and personality in early life: sexual differences in signalling
(Wiley Online Library, 2019) López-Idiaquez, David; Fargallo, Juan Antonio; López-Rull, Isabel; Martínez-Padilla, Jesús
Several studies have shown that melanin-based traits play a crucial role in social contexts as they are associated with dominance, personality and social behaviour. However, most of these studies have focused on adults, and the role of these traits in juveniles has rarely been explored. Here, we explore the association between two melanin-based traits and nestling personality in Common Kestrels Falco tinnunculus. Our results show that female nestlings with blacker plumages displayed bolder personalities, providing evidence of sex-dependent phenotypic integration of these two traits in males and females. We consider that this differential integration may arise from different selection pressures acting on males and females on plumage coloration during adulthood and that nestling coloration can act as a status signal within the juvenile age-class.
Settlement Phenotypes: Social Selection and Immigration in a Common Kestrel Population
(Frontiers in Ecology and Evolution, 2022) Fargallo, Juan Antonio; López-Rull, Isabel
Dispersal decisions are affected by the internal state of the individual and the external environment. Immigrants entering a new population are phenotypically different from residents due to selection that mitigate costs of dispersal and facilitate settlement. Sexual and status signaling traits may influence individual’s ability to settle in a population, either by showing a subordinate phenotype thus reducing aggressive interactions, or by signaling a more competitive phenotype, thus gaining local breeding resources, including mates. By comparing immigrants vs. residents in a common kestrel population across 17 years, we evaluated the influence of dispersal on fitness components (laying date, clutch size and number of fledglings) and investigated if sex, age and phenotypic traits (body size, body condition and plumage coloration) involved in movement and social interactions affected settlement. We found that population characteristics affected sexes and age classes differently, as the admission of females and young males into our population had fewer obstacles than the admission of males. In females, immigrant young were larger, had longer wings and tails, showed better body condition, had less gray tails, started breeding earlier, and laid larger clutches than residents. Adult female immigrants also showed better body condition and less gray tails. In males, immigrants had longer tails and higher number of black spots than residents. Summarizing, immigrants are good-quality individuals and, as deduced from their breeding performance, they benefited by signaling subordination, thus reducing the probability of aggressive encounters and facilitating settlement. Our study highlights the role of phenotypic traits related to signaling to study dispersal
Sex-specific phenotypic integration: endocrine profiles, coloration, and behavior in fledgling boobies
(International Society for Behavioral Ecology, 2014) Fargallo, Juan Antonio; Velando, Alberto; López-Rull, Isabel; Gañán, Natalia; Lifshitz, Natalia; Wakamatsu, Kazumasa; Torres, Roxana
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.