The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potential...The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potentially negative consequences on physiology mediated by oxidative stress.In addition,telomere length(TL)undergoes reduction during birds’early life,partly depending on oxidative status.However,relatively few studies have focused specifically on the changes in oxidative status and TL that occur immediately after hatching.In this study of the yellow-legged gull Larus michahellis,we found that chicks undergo a marked increase in plasma total antioxidant capacity and a marked decrease in the concentration of pro-oxidant molecules during the first days after hatching.In addition,TL in erythrocytes decreased by 1 standard deviation over the 4days post-hatching.Body mass and tarsus length covaried with total antioxidant capacity and concentration of pro-oxidants in a complex way,that partly depended on sex and laying order,suggesting that oxidative status can affect growth.Moreover,TL positively covaried with the concentration of pro-oxidant molecules,possibly because retention of high concentrations of pro-oxidant molecules results from mechanisms of prevention of their negative effects,including reduction in TL.Thus,this study shows that chicks undergo marked variation in oxidative status,which predicts growth and subsequent TL,prompting for more studies of the perinatal changes in the critical posthatching stages.展开更多
Parental effects occur whenever the phenotype of parents or the environment that they experience influences the phenotype and fitness of their offspring, In birds, parental effects are often mediated by the size and b...Parental effects occur whenever the phenotype of parents or the environment that they experience influences the phenotype and fitness of their offspring, In birds, parental effects are often mediated by the size and biochemical quality of the eggs in terms of maternally transferred components. Exogenous antioxidants are key egg components that accomplish crucial physiological functions during early life. Among these, vitamin E plays a vital role during prenatal development when the intense metabolism accompanying rapid embryo growth results in overproduction of pro-oxidant molecules. Studies of captive birds have demonstrated the positive effect of vitamin E supplementation on diverse phenotypic traits of hatchling and adult individuals, but its effects on embryo phenotype has never been investigated neither in captivity nor under a natural selection regime. In the present study, we experimentally tested the effect of the in ovo supplementation of vitamin E on morphological traits and oxidative status of yellow-legged gull （Larus michahellis） embryos. The supplementation of vitamin E promoted somatic growth in embryos soon before hatching, but did not affect their oxidative status. Our results suggest that maternally transferred vitamin E concentrations are optimized to prevent imbalances of oxidative status and the consequent raise of oxidative damage in yellow-legged gull embryos during prenatal development.展开更多
Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evol tion. Here, we experim...Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evol tion. Here, we experime ntally tested such non-lethal effects of exposure to in creased predati on risk on clutch size, egg mass, and the concentration of yolk steroid hormones in the yellow-legged gull Larus michahellis. We simulated increased predation risk by displaying stuffed predators (adult fox Vulpes vulpes, and adult buzzard Buteo buteo) to breeding adults before egg laying. The concentration of corticosterone, which has bee n show n to in crease un der exposure to mater nal predati on risk in other species, and of testosterone did not differ between eggs from mothers exposed to the predators and eggs from control mothers (i.e., eggs exposed to a novel object of similar size and position to the stuffed predators). The concentration of the two hormones negatively covaried. Clutch size did not vary according to experimental treatment, whereas egg mass was markedly larger in clutches from n ests exposed to predators than in clutches from control n ests. By in creasing egg mass, mothers may reduce the risk of cooling of the eggs when incubation is impeded by predators, boost energy reserves, reduce post-natal detectability caused by food solicitation, and/ or enha nee developme nt at hatchi ng, thus increasing the cha nces of offspri ng survival. In general, our results are inconsistent with most of the few previous studies on similar non-lethal predator effects and suggest that such effects may vary among species according to ecological conditions, social behavior, and developmental mode.展开更多
文摘The perinatal period is critical to survival and performance of many organisms.In birds,rapid postnatal growth and sudden exposure to aerial oxygen around hatching markedly affect the chick redox status,with potentially negative consequences on physiology mediated by oxidative stress.In addition,telomere length(TL)undergoes reduction during birds’early life,partly depending on oxidative status.However,relatively few studies have focused specifically on the changes in oxidative status and TL that occur immediately after hatching.In this study of the yellow-legged gull Larus michahellis,we found that chicks undergo a marked increase in plasma total antioxidant capacity and a marked decrease in the concentration of pro-oxidant molecules during the first days after hatching.In addition,TL in erythrocytes decreased by 1 standard deviation over the 4days post-hatching.Body mass and tarsus length covaried with total antioxidant capacity and concentration of pro-oxidants in a complex way,that partly depended on sex and laying order,suggesting that oxidative status can affect growth.Moreover,TL positively covaried with the concentration of pro-oxidant molecules,possibly because retention of high concentrations of pro-oxidant molecules results from mechanisms of prevention of their negative effects,including reduction in TL.Thus,this study shows that chicks undergo marked variation in oxidative status,which predicts growth and subsequent TL,prompting for more studies of the perinatal changes in the critical posthatching stages.
文摘Parental effects occur whenever the phenotype of parents or the environment that they experience influences the phenotype and fitness of their offspring, In birds, parental effects are often mediated by the size and biochemical quality of the eggs in terms of maternally transferred components. Exogenous antioxidants are key egg components that accomplish crucial physiological functions during early life. Among these, vitamin E plays a vital role during prenatal development when the intense metabolism accompanying rapid embryo growth results in overproduction of pro-oxidant molecules. Studies of captive birds have demonstrated the positive effect of vitamin E supplementation on diverse phenotypic traits of hatchling and adult individuals, but its effects on embryo phenotype has never been investigated neither in captivity nor under a natural selection regime. In the present study, we experimentally tested the effect of the in ovo supplementation of vitamin E on morphological traits and oxidative status of yellow-legged gull （Larus michahellis） embryos. The supplementation of vitamin E promoted somatic growth in embryos soon before hatching, but did not affect their oxidative status. Our results suggest that maternally transferred vitamin E concentrations are optimized to prevent imbalances of oxidative status and the consequent raise of oxidative damage in yellow-legged gull embryos during prenatal development.
文摘Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evol tion. Here, we experime ntally tested such non-lethal effects of exposure to in creased predati on risk on clutch size, egg mass, and the concentration of yolk steroid hormones in the yellow-legged gull Larus michahellis. We simulated increased predation risk by displaying stuffed predators (adult fox Vulpes vulpes, and adult buzzard Buteo buteo) to breeding adults before egg laying. The concentration of corticosterone, which has bee n show n to in crease un der exposure to mater nal predati on risk in other species, and of testosterone did not differ between eggs from mothers exposed to the predators and eggs from control mothers (i.e., eggs exposed to a novel object of similar size and position to the stuffed predators). The concentration of the two hormones negatively covaried. Clutch size did not vary according to experimental treatment, whereas egg mass was markedly larger in clutches from n ests exposed to predators than in clutches from control n ests. By in creasing egg mass, mothers may reduce the risk of cooling of the eggs when incubation is impeded by predators, boost energy reserves, reduce post-natal detectability caused by food solicitation, and/ or enha nee developme nt at hatchi ng, thus increasing the cha nces of offspri ng survival. In general, our results are inconsistent with most of the few previous studies on similar non-lethal predator effects and suggest that such effects may vary among species according to ecological conditions, social behavior, and developmental mode.
