Starting with a handicap: phenotypic differences between early‐ and late‐born king penguin chicks and their survival correlates

Abstract

Summary1. The exceptionally long (c. 11 months) growth period of king penguin chicks (Aptenodytes patagonicus) is interrupted by the Austral winter. As a consequence, penguin chicks born late in the breeding season have little time to build-up their energy reserves before the drastic energy bottleneck they experience during winter and face greater risks of mortality than earlyborn chicks. 2. Whereas it is well known that breeding adults alternate between early-and late-breeding attempts, little is known on the phenotype of early-and late-chicks, and on the potential existence of specific adaptive phenotypic responses in late-born individuals. 3. We investigated phenotypic differences between early-and late-chicks and tested their survival correlates both before the winter and at fledgling. Chicks were sampled 10 days after hatching to measure body mass, plasma corticosterone levels, oxidative stress parameters and telomere length. 4. Late-chicks were heavier than early-chicks at day 10. Late-chicks also had higher corticosterone and oxidative stress levels, shorter telomere lengths and suffered from higher mortality rates than early-chicks. For both early-and late-chicks, high body mass close to hatching was a strong predictor of survival up to, and over, the winter period. 5. In late but not early-chicks, high corticosterone levels and long telomeres were significant predictors of survival up to winter and fledging, respectively. 6. Our study provides evidence that late-and early-king penguin chicks showed marked phenotypic differences 10 days after hatching. We provide an integrative discussion on whether these differences may be adaptive or not, and to what extent they may be driven by active maternal effects, indirectly induced by environmental effects, or stem from individual differences in parental quality.

Oxidative stress in aspic vipers facing pregnancy and water constraints

“…Measuring telomere length could prove fruitful for future research on the cost of reproduction and dehydration in this species, as short telomeres have been shown to predict lower survival probability in several captive and wild animal species (Stier et al, 2015a). Furthermore, telomeres have been shown to shorten in response to both increased reproductive effort (Reichert et al, 2014) and stressful environmental conditions (Stier et al, 2014b(Stier et al, , 2015bMeillere et al, 2015;Simide et al, 2016). Additionally, recent work suggests that changes in mitochondrial bioenergetics and ROS production during reproduction are potential key mechanisms underlying the costs of reproduction (Zhang and Hood, 2016).…”

Environmental conditions can modulate the links among oxidative stress, age, and longevity

“…For example, studies in mice genetically modified to increase exposure to ROS via altering specific antioxidants, generally showed no effect on the probability of survival, but rather contributed to the progression of diseases (Salmon et al 2010). The recent growing body of work in un-manipulated individuals primarily carried out in free-living bird populations has also shown mixed results (reviewed in Costantini, 2014), with some studies supporting the idea of negative association among markers of oxidative damage and survival (Freeman-Gallant et al 2011;Noguera et al 2012, Costantini et al 2015a, Herborn et al 2015, and others reporting no association (Beaulieu et al 2011;Stier et al 2014c;Costantini et al 2015b). The variable outcomes may be due to several factors, including species-specific patterns, differences in life-stages between individuals (e.g.…”

Maternal basking regime has complex implications for birthdate and offspring phenotype in a nocturnally foraging, viviparous gecko

“…Examples exist across varied taxa and parity modes, including an association of early birthdate with adoption of an alternative reproductive tactic in male fish (Fagundes et al, 2015), with greater survival and larger mass at first summer's end in penguin chicks (Stier et al, 2014), and with greater survival (at high population density) in squirrels (Williams et al, 2014). In principle, effects on offspring from time of birth may arise from: (1) seasonal variation in the quality of the environment into which offspring are born; (2) variation in the quality of offspring themselves, arising from prenatal developmental effects; and (3) in those species that provide it, variation in parental care during the postnatal period (Wapstra et al, 2010;Stier et al, 2014). Birthdate can also influence a mother's readiness for future reproduction (e.g.…”