Biology subjects

Blanchard, P.

Publications and source records attributed to Blanchard, P..

4 recordsLinked to original sources

bioRxiv2026

The king of stress? Exploring the physiological resilience and resistance of adult king penguins to chronic glucocorticoid exposure

To better understand how animals cope with increasingly variable and challenging environments, there is a need to study how prolonged exposure to elevated glucocorticoid hormones (i.e. one mediator of the stress response) affects their physiology. While glucocorticoid elevation is known to increase oxidative stress and accelerate cellular ageing, there is evidence that king penguins (Aptenodytes patagonicus) can prevent oxidative stress during acute stress exposure, suggesting that species may differ in their sensitivity to glucocorticoids downstream negative effects. As king penguins thrive in a seemingly harsh environment, we hypothesized that they may be able to limit the deleterious effects usually associated with chronic glucocorticoid elevation, either through resistance (i.e. prevention of downstream negative effect) or resilience (i.e. rapid recovery following transient negative effect). To test this hypothesis, we experimentally elevated corticosterone levels in incubating king penguins and quantified treatment effects on a suite of physiological traits at multiple time points across incubation and early chick-rearing, up to ca. 2 months after implantation. Corticosterone-treated individuals showed a prolonged increase in corticosterone and decrease in body condition, confirming our treatment likely mimicked sustained stress exposure. Heterophil-to-lymphocyte ratio was only increased transiently, and there was no clear evidence that treatment influenced oxidative stress or telomere length maintenance. Plasma energy metabolites were mainly affected early after implantation, with rapid recovery over time. Overall, our results suggest that adult king penguins show at least moderate resistance and resilience to chronic corticosterone elevation, especially in preventing cellular integrity loss, though at-sea physiological effects remain to be determined.

physiology↗

bioRxiv2025

Flexible foraging effort shapes Adelie penguin reproductive success across Antarctica and sea ice conditions

Understanding how species deal with diverse environmental conditions is crucial for predicting their future responses to climate change. In Antarctica, changing sea ice dynamics threaten ice-dependent species. Whilebehavioural adjustmentscould help mitigate these threats, their effectiveness under future environmental conditions and potential thresholds remain unclear. Long-term studies and circumpolar approaches could address this challenge. Our 15-year study (2010-2024) of over 23,000 foraging trips from Adelie penguins (Pygoscelis adeliae) in East Antarctica, identified a non-linear relationship between sea ice concentration (SIC) and foraging effort when landfast ice was absent, a situation anticipated to define the species future habitat during chick-rearing. Minimal effort occurred at 10-20% SIC, but more than doubled with the presence of landfast ice or heavy pack-ice, with females showing greater sensitivity to these ice changes. Acircumpolar analysis of similar data demonstrated that foraging effort during chick-guarding predicted reproductive success across ten Adelie penguin populations. Reproductive success remained high until foraging trips exceeded approximately 29 hours, after which performance declined sharply. This indicates that while behavioural flexibility can buffer against moderate environmental changes, it has clear limits. Our findings establish foraging trip duration as a valuable early warning indicator for population responses to environmental change.

ecology↗

bioRxiv2024

Sex-specific mate choice and mate change based on MHC-IIB dissimilarity in a genetically monogamous seabird

Among species reproducing sexually, mating strategies represent a major component of individual fitness. The major histocompatibility complex (MHC) is an extremely diverse set of genes responsible for immunological recognition and defence against pathogens. Although dissimilarity between mates at the major histocompatibility complex has been proposed to drive mate choice through increased offspring pathogen resistance, evidence is mixed. In addition, explorations of the role of the major histocompatibility complex in other mating strategies, such as divorce, are rare. We investigated whether dissimilarity at the major histocompatibility complex class IIB is associated with mate choice and divorce probability in the genetically monogamous black-legged kittiwake (Rissa tridactyla). We found that first-time male breeders, as well as divorced males, were paired with females more dissimilar at the major histocompatibility complex class IIB than expected under random mating. We did not find evidence for mate choice based on major histocompatibility complex class IIB dissimilarity when considering females. In addition, in the studied population, divorce probability was very low compared with other populations and did not significantly vary with the dissimilarity of the pair at the major histocompatibility complex class IIB. Our results pave the way to a better understanding of the complex role of major histocompatibility complex dissimilarity in mating decisions of species displaying mutual choice and biparental care.

animal behavior and cognition↗

bioRxiv2024

Declining juvenile survival of Adelie penguins in Antarctica

As summer sea ice around Antarctica reaches modern lows, quantifying the demographic response of polar species to such environmental changes becomes critical. To achieve this, synthesizing results across species ranges and elucidating the environmental factors driving population dynamics are key. Adelie penguins are considered reliable indicators of changes in Antarctica but the processes through which sea ice and other environmental factors shape their population dynamics are still unclear, especially for critical age groups such as juveniles. Using a 17-year dataset of Adelie penguins electronically tagged in Adelie Land (Antarctica), we found that juvenile survival probability was most impacted by sea ice concentration near their natal colony right after fledging, with lower ice concentrations detrimental to survival. Importantly, we found that juvenile survival declined by 32% from 2007 to 2020, mirroring trends at other distant colonies. The emergence of similar patterns at opposite ends of the continent may be an early signal for shifts in population trends expected from climate change.

ecology↗