Abstract: 1.Surviving prolonged food deprivation requires various metabolic adaptations such as energy and protein sparing, which can be highly conflicting with energy-demanding stages of an animals life history such as growth. 2.Due to the maternal attendance pattern, subantarctic fur seal (Arctocephalus tropicalis Gray) pups must repeatedly endure exceptionally long fasts of increasing duration throughout the 10-month lactation period. Little is known of (i) how these infants adapt to such extreme energetic constraints while sustaining growth and development; and (ii) the ecological implications of repeated prolonged fasting in early life in terms of offspring survival, maternal care and growth strategy in this species, as well as the evolutionary consequences of such life history trait. 3.Physiological responses to prolonged fasting and how they change with development throughout the pre-weaning period were investigated. Results show that beginning with their first fast, subantarctic fur seal pups are able to mobilize lipid reserves preferentially while conserving protein stores in response to nutritional deprivation. As pup age, profound changes in energy expenditure allow the implementation of an efficient strategy of fat storage and lean body mass preservation, which proves highly adaptive in the face of the low maternal provisioning rates experienced. 4.Despite increasing fasting durations, pup mortality decreased markedly throughout the maternal dependence period. Consistent with predictions, field measurements indicate that fasting endurance, although limited in early life, increases up to durations of nearly 3 months with age. Results suggest that the maternal provisioning strategy could be constrained by these ontogenetic changes in pup fasting abilities. 5.Furthermore, extreme energetic constraints and local density-dependent effects appear to exert a strong selective pressure upon the adoption of a convergent growth strategy between the sexes aiming to maximize fat storage and pre-weaning survival. 6.The issues of resulting trade-offs between pre- and post-weaning survival and the evolutionary consequences of extreme fasting abilities are also addressed.

Abstract: Species in which the sexes equally exhibit colourful ornaments are an issue for evolutionary theory. Among several hypotheses, sexual selection for mutual mate choice and social selection for signals of behavioural dominance are most commonly supported. We examined the previously documented sex-similar size of yellow-orange ear patches in the king penguin, Aptenodytes patagonicus. This species is monogamous and pairs just before reproduction. Raising a chick requires considerable effort by both parents, as they alternate care of their single offspring with foraging at sea. The size of the ear patches appears to signal aggressive territoriality in the breeding colony for both sexes. However, experiments suggest that females prefer large patch size during mate choice, and males do not prefer this trait. We tested whether the size of the coloured ear patch was influenced by sexual selection for couples that had recently paired. We used analyses of covariance to compare the size of the ear patch to a measure of body size and then tested for the difference between males and females. Males were 6.2% larger in ear patch width and 7.7% larger in ear patch area than females, and the distance between the ear patches over the head was 7.5% smaller in males, with all differences highly significant. Consequently, sexual selection appears to favour larger ear patches in males, possibly because of an excess of males that promotes female choice. Social selection also appears to favour the evolutionary maintenance of ear patches of males, and thus both types of selection may contribute to enlarged ear patches.

Abstract: 1.Stable isotopes are increasingly used in ecology to investigate ontogenetic shifts in foraging habitat (via 13C) and in trophic level (via 15N). These shifts are in essence an individual-level phenomenon, requiring repeated measures throughout the life of individuals, i.e. longitudinal data. Longitudinal data require in turn specifying an appropriate covariance structure. Here we present a hierarchical model to jointly investigate individual ontogenetic shifts in 13C and 15N values. 2.In a Bayesian framework, we used a Cholesky decomposition for estimating a moderately-sized covariance matrix, thereby directly estimating correlations between parameters describing time-series of isotopic measurements. We offer guidelines on how to select the covariance structure. 3.The approach is illustrated with a hierarchical change-point (or broken stick) model applied to a data set collected on Southern Elephant Seals, Mirounga leonina. Ontogenetic shifts in foraging habitat, following a juvenile and variable stage, were detected and interpreted as fidelity to a foraging strategy; while ontogenetic shifts in trophic level were more likely the result of complete independence from maternal resources followed by a gradual increase in trophic level as seals aged. 4.Specifying both an appropriate covariance and mean structure enabled us to draw strong inferences on the ecology of an elusive marine predator, and has wide applicability for isotopic ecology provided repeated isotopic measurements are available.

Abstract: 1.Despite a growing interest in wildlife disease ecology, there is a surprising lack of knowledge about the exposure dynamics of individual animals to naturally circulating infectious agents and the impact of such agents on host life-history traits. 2.The exploration of these questions requires detailed longitudinal data on individual animals that can be captured multiple times during their life but also requires being able to account for several sources of uncertainty, notably the partial observation or recapture of individuals at each sampling occasion. 3.We use a multi-year dataset to (i) assess the potential effect of exposure to the tick-borne agent of Lyme disease, Borrelia burgdorferi sensu lato (Bbsl), on adult apparent survival for one of its natural long-lived hosts, the Black-legged kittiwake (Rissa tridactyla), and (ii) investigate the temporal dynamics of individual immunological status in kittiwakes to infer the rate of new exposure and the persistence of the immune response. Using a multi-event modelling approach, potential uncertainties arising from partial observations were explicitly taken into account. 4.The potential impact of Bbsl on kittiwake survival was also evaluated via an experimental approach: the apparent survival of a group of breeding birds treated with an antibiotic was compared with that of a control group. 5.No impact of exposure to Bbsl was detected on adult survival in kittiwakes, in either observational or experimental data. 6.An annual seroconversion rate (from negative to positive) of 1·5% was estimated, but once an individual became seropositive, it remained so with a probability of 1, suggesting that detectable levels of anti-Bbsl antibodies persist for multiple years. 7.These results, in combination with knowledge on patterns of exposure to the tick vector of Bbsl, provide important information for understanding the spatio-temporal nature of the interaction between this host and several of its parasites. Furthermore, our analyses highlight the utility of capturemarkrecapture approaches handling state uncertainty for disease ecology studies.

Abstract: Sexual dimorphism is widely used as an indirect measure of the intensity of sexual selection. It is also a way to evaluate whether different selective pressures act on males and females. Dichromatism, defined as a difference in colouration between males and females, may for instance result from selection for crypsis in females and selection for conspicuousness in males. Here, we conducted a study to investigate whether differential sexual selective pressures might act on the colour traits of two colonial seabird species, the Atlantic puffin Fratercula artica and the black-legged kittiwake Rissa tricactyla. First, we used spectrophotometry and visual modelling to determine whether these presumed monomorphic birds are really monochromatic from an avian perspective (birds and humans have a different vision). Second, we estimated whether some of their colourations have the potential to be sexually or socially selected by determining whether these colourations were related to body condition in males and females, and whether the yellow, orange and red colourations may contain carotenoid pigments. Our results indicated that both species were fully monochromatic from an avian perspective. Moreover, our preliminary analyses suggested that the yellow, orange and red colours of these birds contained carotenoids. Lastly, some indices of colouration were positively linked to estimates of condition. Birds in better condition had redder gape (both species) and bill (puffins). In puffins, the relation between condition and gape colouration was significantly stronger in females than males. By contrast, the size of the gape rosette was larger in males than females. The positive links we found between colour indices and condition, together with the absence of sexual dichromatism, suggest that mutual sexual selection may act in these two species.