Effects of Individual Pre-Fledging Traits and Environmental Conditions on Return Patterns in Juvenile King Penguins

Despite the importance of early life stages in individuals' life history and population dynamics, very few studies have focused on the constraints to which these juvenile traits are subjected. Based on 10 years of automatic monitoring of over 2500 individuals, we present the first study on the effects of environmental conditions and individual pre-fledging traits on the post-fledging return of non-banded king penguins to their natal colony. Juvenile king penguins returned exclusively within one of the three austral summers following their departure. A key finding is that return rates (range 68–87%) were much higher than previously assumed for this species, importantly meaning that juvenile survival is very close to that of adults. Such high figures suggest little juvenile dispersal, and selection occurring mostly prior to fledging in king penguins. Pre-fledging conditions had a strong quadratic impact on juvenile return rates. As expected, cohorts reared under very unfavourable years (as inferred by the breeding success of the colony) exhibited low return rates but surprisingly, so did those fledged under very favourable conditions. Juvenile sojourns away from the colony were shorter under warm conditions and subsequent return rates higher, suggesting a positive effect of climate warming. The longer the post-fledging trip (1, 2 or 3 years), the earlier in the summer birds returned to their natal colony and the longer they stayed before leaving for the winter journey. The presence of juveniles in the colony was more than twice the duration required for moulting purposes, yet none attempted breeding in the year of their first return. Juvenile presence in the colony may be important for acquiring knowledge on the social and physical colonial environment and may play an important part in the learning process of mating behaviour. Further studies are required to investigate its potential implications on other life-history traits such as recruitment age

Sardines at a junction: seascape genomics reveals ecological and oceanographic drivers of variation in the {NW} Mediterranean Sea

By evaluating genetic variation across the entire genome, one can address existing questions in a novel way while raising new ones. The latter includes how different local environments influence adaptive and neutral genomic variation within and among populations, providing insights into local adaptation of natural populations and their responses to global change. Here, under a seascape genomic approach, ddRAD data of 4609 single nucleotide polymorphisms (SNPs) from 398 sardines (Sardina pilchardus) collected in 11 Mediterranean and one Atlantic site were generated. These were used along with oceanographic and ecological information to detect signals of adaptive divergence with gene flow across environmental gradients. The studied sardines constitute two clusters (FST = 0.07), a pattern attributed to outlier loci, highlighting putative local adaptation. The trend in the number of days with sea surface temperature above 19°C, a critical threshold for successful sardine spawning, was crucial at all levels of population structuring with implications on the species' key biological processes. Outliers link candidate SNPs to the region's environmental heterogeneity. Our findings provide evidence for a dynamic equilibrium in which population structure is maintained by physical and ecological factors under the opposing influences of migration and selection. This dynamic in a natural system warrants continuous monitoring under a seascape genomic approach that might benefit from a temporal and more detailed spatial dimension. Our results may contribute to complementary studies aimed at providing deeper insights into the mechanistic processes underlying population structuring. Those are key to understanding and predicting future changes and responses of this highly exploited species in the face of climate change

Habitat Suitability Modeling to Identify the Potential Nursery Grounds of the Atlantic Mackerel and Its Relation to Oceanographic Conditions in the Mediterranean Sea

Our knowledge for the distribution of Atlantic mackerel (Scomber scombrus) in the Mediterranean Sea is limited and fragmented. In the current work habitat suitability modeling was applied to summer acoustic surveys data of Atlantic mackerel juveniles derived from the north part of the Mediterranean (i.e., acoustic data from the Gulf of Lions, pelagic trawls held during acoustic surveys in Spanish Mediterranean waters, south Adriatic Sea, Strait of Sicily, and North Aegean Sea) using generalized additive models (GAMs) along with satellite environmental and bathymetry data. Bathymetry along with sea surface temperature and circulation patterns, expressed through sea level anomaly and the zonal component of the absolute geostrophic velocity, were the environmental variables best to describe nursery grounds. The selected model was used to produce maps presenting the potential nursery grounds of Atlantic mackerel throughout the Mediterranean Sea as a measure of habitat adequacy. However, the assessed potential nursery grounds were generally marked as “occasional,” implying that although there are areas presenting high probability to encounter Atlantic mackerel, this picture can largely vary from year to year stressing the high susceptibility of the species to environmental conditions. In a further step and toward a spatial management perspective, we have estimated and visualized the overlap between Atlantic mackerel and anchovy/ sardine juvenile grounds throughout the basin. Results showed that although the degree of overlapping was generally low, not exceeding 15% in general, this varied at a regional level going up to 30%. The potential of the output of this work for management purposes like the implementation of spatially-explicit management tools is discussedVersión del edito

It Costs to Be Clean and Fit: Energetics of Comfort Behavior in Breeding-Fasting Penguins

), seabirds known to fast for up to one month during incubation shifts ashore.A time budget was estimated from focal and scan sampling field observations and the energy cost of comfort activities was calculated from the associated increase in heart rate (HR) during comfort episodes, using previously determined equations relating HR to energy expenditure. We show that incubating birds spent 22% of their daily time budget in comfort behavior (with no differences between day and night) mainly devoted to preening (73%) and head/body shaking (16%). During comfort behavior, energy expenditure averaged 1.24 times resting metabolic rate (RMR) and the corresponding energy cost (i.e., energy expended in excess to RMR) was 58 kJ/hr. Energy expenditure varied greatly among various types of comfort behavior, ranging from 1.03 (yawning) to 1.78 (stretching) times RMR. Comfort behavior contributed 8.8–9.3% to total daily energy expenditure and 69.4–73.5% to energy expended daily for activity. About half of this energy was expended caring for plumage.This study is the first to estimate the contribution of comfort behavior to overall energy budget in a free-living animal. It shows that although breeding on a tight energy budget, king penguins devote a substantial amount of time and energy to comfort behavior. Such findings underline the importance of comfort behavior for the fitness of colonial seabirds

Symptom-based stratification of patients with primary Sjögren's syndrome: multi-dimensional characterisation of international observational cohorts and reanalyses of randomised clinical trials

Background Heterogeneity is a major obstacle to developing effective treatments for patients with primary Sjögren's syndrome. We aimed to develop a robust method for stratification, exploiting heterogeneity in patient-reported symptoms, and to relate these differences to pathobiology and therapeutic response. Methods We did hierarchical cluster analysis using five common symptoms associated with primary Sjögren's syndrome (pain, fatigue, dryness, anxiety, and depression), followed by multinomial logistic regression to identify subgroups in the UK Primary Sjögren's Syndrome Registry (UKPSSR). We assessed clinical and biological differences between these subgroups, including transcriptional differences in peripheral blood. Patients from two independent validation cohorts in Norway and France were used to confirm patient stratification. Data from two phase 3 clinical trials were similarly stratified to assess the differences between subgroups in treatment response to hydroxychloroquine and rituximab. Findings In the UKPSSR cohort (n=608), we identified four subgroups: Low symptom burden (LSB), high symptom burden (HSB), dryness dominant with fatigue (DDF), and pain dominant with fatigue (PDF). Significant differences in peripheral blood lymphocyte counts, anti-SSA and anti-SSB antibody positivity, as well as serum IgG, κ-free light chain, β2-microglobulin, and CXCL13 concentrations were observed between these subgroups, along with differentially expressed transcriptomic modules in peripheral blood. Similar findings were observed in the independent validation cohorts (n=396). Reanalysis of trial data stratifying patients into these subgroups suggested a treatment effect with hydroxychloroquine in the HSB subgroup and with rituximab in the DDF subgroup compared with placebo. Interpretation Stratification on the basis of patient-reported symptoms of patients with primary Sjögren's syndrome revealed distinct pathobiological endotypes with distinct responses to immunomodulatory treatments. Our data have important implications for clinical management, trial design, and therapeutic development. Similar stratification approaches might be useful for patients with other chronic immune-mediated diseases. Funding UK Medical Research Council, British Sjogren's Syndrome Association, French Ministry of Health, Arthritis Research UK, Foundation for Research in Rheumatology

Réponse des manchots face aux changements environnementaux,de l'individu à la population

Le changement climatique, dorénavant sans équivoque, devrait se poursuivre voire s'amplifier dans les siècles à venir, affectant profondément la composante biologique de notre planète. Il est donc nécessaire et urgent de mieux comprendre les écosystèmes eClimate change is now unequivocal and foreseen to continue within the next centuries, profoundly affecting the biological component of our planet. Thus, it is becoming urgently necessary to increase our understanding of ecosystems and their responses to

Response of penguins to environmental changes across the Southern Ocean : from individuals to population trends

Le changement climatique, dorénavant sans équivoque, devrait se poursuivre voire s’amplifier dans les siècles à venir, affectant profondément la composante biologique de notre planète. Il est donc nécessaire et urgent de mieux comprendre les écosystèmes et leurs réponses face au changement climatique. Au cours de cette thèse, j’ai étudié l’effet du climat dans l’Océan Austral au travers des manchots. Ceux-ci sont souvent considérés comme de bons indicateurs de leurs écosystèmes de part leur position au sommet de la chaîne trophique. Ce travail repose sur des données pluriannuelles collectées sur 3 espèces de manchots à l’aide de systèmes de suivi automatique, visant à minimiser la perturbation par rapport à la méthode habituelle des bagues alaires. Ainsi, nous montrons des effets contrastés du climat sur les différents traits d’histoire de vie chez les manchots royaux, dont la survie juvénile augmentait les années où la température de surface de la mer était élevée, au contraire de la survie adulte et du succès reproducteur. De plus, nous soulignons l’importance de l’échelle temporelle à laquelle on étudie cet effet du climat et la nécessité de l’adapter à la biologie de l’espèce. La mortalité des poussins de manchots pygmées est par exemple concentrée sur quelques semaines, indiquant que le succès reproducteur dépend chez cette espèce de conditions ponctuelles et non des moyennes saisonnières généralement utilisées. Enfin, les capacités différentes des individus à faire face à des conditions de glace variables, observées chez le manchot Adélie, montrent la nécessité de prendre en compte les différences interindividuelles en vue d’une potentielle adaptation des manchots.Climate change is now unequivocal and foreseen to continue within the next centuries, profoundly affecting the biological component of our planet. Thus, it is becoming urgently necessary to increase our understanding of ecosystems and their responses to climate change. In this thesis, we investigated the effects of climate on Southern Ocean ecosystems through the monitoring of penguins. As top-predators, penguins are often considered good indicators of their environment by integrating the effects of climate which occur lower in the food chain. Data were collected over several years on 3 penguin species (little, king and Adélie penguins) using automatic monitoring systems, that we proved to be relatively harm-free compared to the usual but deleterious flipper-banding method. We found king penguin juvenile survival to increase in years of high sea surface temperature by opposition to previous results on adult survival and breeding success, indicating contrasted effects of climate depending on life-history traits. Also, we highlighted the importance of the time-scale at which the effect of climate is investigated and the necessity of adapting it to the species biology. In little penguins, chick mortality was concentrated on some weeks, underlining the dependence of breeding success on punctual conditions instead of the mostly used mean seasonal conditions. Finally, we showed the importance of individual heterogeneity, leading for instance to differences in the ability to face various sea-ice conditions in Adélie penguins. Such inter-individual differences along with behavioural flexibility may play a role in a potential penguin adaption through phenotypic plasticity