Dietary carotenoid availability influences a male's ability to provide parental care

Despite convincing evidence that carotenoid availability can have positive physiological effects, we still lack information on the functional consequences of carotenoid limitation at the behavioral level. Given the role carotenoids play in mitigating oxidative stress produced during physical activity and as immunostimulants, one behavioral function on which they may have a significant impact is an individual's capacity to provide parental care. We tested this hypothesis using three-spined sticklebacks (Gasterosteus aculeatus), a species in which males provide obligate and intensive paternal care. Males were fed either high or low (but biologically realistic) levels of carotenoids and monitored throughout incubation, during which we quantified 2 key aspects of parental care: their ability to fan their eggs under normoxic and hypoxic conditions (when both the costs and requirements of fanning increase) and their ability to defend their nest against a simulated conspecific male. High-carotenoid diet males fanned their eggs at a significantly higher rate during hypoxic (but not normoxic) conditions and had higher clutch hatching success than males fed the low-carotenoid diet. There was no evidence that they defended their nest more aggressively. Furthermore, low-carotenoid diet males also appeared to engage in cannibalization of their clutch. These results demonstrate that dietary carotenoid availability can affect a male's ability to provide parental care, and we discuss the potential mechanisms and implications of this finding.