| 1. |
- Elliott, Kyle H., et al.
(författare)
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Age-related variation in energy expenditure in a long-lived bird within the envelope of an energy ceiling
- 2014
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 83:1, s. 136-146
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Tidskriftsartikel (refereegranskat)abstract
- Energy expenditure in wild animals can be limited (i) intrinsically by physiological processes that constrain an animal's capacity to use energy, (ii) extrinsically by energy availability in the environment and/or (iii) strategically based on trade-offs between elevated metabolism and survival. Although these factors apply to all individuals within a population, some individuals expend more or less energy than other individuals. To examine the role of an energy ceiling in a species with a high and individually repeatable metabolic rate, we compared energy expenditure of thick-billed murres (Uria lomvia) with and without handicaps during a period of peak energy demand (chick-rearing, N=16). We also compared energy expenditure of unencumbered birds (N=260) across 8years exhibiting contrasting environmental conditions and correlated energy expenditure with fitness (reproductive success and survival). Murres experienced an energy ceiling mediated through behavioural adjustments. Handicapped birds decreased time spent flying/diving and chick-provisioning rates such that overall daily energy expenditure remained unchanged across the two treatments. The energy ceiling did not reflect energy availability or trade-offs with fitness, as energy expenditure was similar across contrasting foraging conditions and was not associated with reduced survival or increased reproductive success. We found partial support for the trade-off hypothesis as older murres, where prospects for future reproduction would be relatively limited, did overcome an energy ceiling to invest more in offspring following handicapping by reducing their own energy reserves. The ceiling therefore appeared to operate at the level of intake (i.e. digestion) rather than expenditure (i.e. thermal constraint, oxidative stress). A meta-analysis comparing responses of breeding animals to handicapping suggests that our results are typical: animals either reduced investment in themselves or in their offspring to remain below an energy ceiling. Across species, whether a handicapped individual invested in its own energy stores or its offspring's growth was not explained by life history (future vs. current reproductive potential). Many breeding animals apparently experience an intrinsic energy ceiling, and increased energy costs lead to a decline in self-maintenance and/or offspring provisioning.
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| 2. |
- Hicks, Olivia, et al.
(författare)
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Holding time has limited impact on constitutive innate immune function in a long-lived Antarctic seabird, the Adélie penguin : implications for field studies
- 2023
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Ingår i: Biology Open. - : The Company of Biologists. - 2046-6390. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- There is great interest in measuring immune function in wild animals. Yet, field conditions often have methodological challenges related to handling stress, which can alter physiology. Despite general consensus that immune function is influenced by handling stress, previous studies have provided equivocal results. Furthermore, few studies have focused on long-lived species, which may have different stress-immune trade-offs compared to short-lived species that have primarily been tested. Here, we investigate whether capture and handling duration impacts innate immune function in a long-lived seabird, the Adélie penguin (Pygoscelis adeliae). We found no evidence for changes in three commonly used parameters of innate immune function upon holding time of up to 2 h, suggesting that immune function in this species is more robust against handling than in other species. This opens up exciting possibilities for measuring immune function in species with similar life-histories even if samples cannot be taken directly after capture.
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| 3. |
- Le Vaillant, Maryline, et al.
(författare)
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Individual parameters shape foraging activity in breeding king penguins
- 2016
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 27:1, s. 352-362
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Tidskriftsartikel (refereegranskat)abstract
- The variability in individual fitness within a population is likely to be mediated through individual foraging ability and tactics, themselves linked to age-or experience-related processes, but also to differences in individual quality. Not only age, experience, and quality but also sex-related foraging strategies should particularly play an important role in long-lived central-place foragers that have to cope with strong environmental constraints. We monitored the foraging effort (foraging trip durations and number of trips) of 262 known-age micro-tagged king penguins, Aptenodytes patagonicus, at different breeding stages during one of their breeding cycles. We investigated how their age (4-11 years old), sex, past breeding experience (the number of successful breeding attempts), and breeding quality (the expected breeding success, corresponding to the residual of the linear relationship between the age and on the number of past breeding success divided by the number of breeding attempts) affected foraging over a whole breeding season. During the incubation, younger birds (4 years old) undertook longer foraging trips compared with older ones. During the brooding phase and the second period of the creching phase, more experienced birds performed shorter foraging trip than those with a low breeding experience, whereas, during the first period of the creching phase, individuals with better breeding quality performed shorter foraging trips at sea than low breeding quality individuals. Sex-specific foraging patterns were also observed depending on the period of the breeding cycle. Our study shows, for the first time, how foraging effort can be driven by a complex interplay of several individual parameters according to breeding stage and resource availability and abundance.
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| 4. |
- Le Vaillant, Maryline, et al.
(författare)
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Telomere length reflects individual quality in free-living adult king penguins
- 2015
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Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 38:12, s. 2059-2067
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Tidskriftsartikel (refereegranskat)abstract
- Growing evidence suggests that telomeres, non-coding DNA sequences that shorten with age and stress, are related in an undefined way to individual breeding performances and survival rates in several species. Short telomeres and elevated shortening rates are typically associated with life stress and low health. As such, telomeres could serve as an integrative proxy of individual quality, describing the overall biological state of an individual at a given age. Telomere length could be associated with the decline of an array of physiological traits in age-controlled individuals. Here, we investigated the links between individuals' relative telomere length, breeding performance and various physiological (body condition, natural antibody levels) and life history (age, past breeding success) parameters in a long-lived seabird species, the king penguin Aptenodytes patagonicus. While we observed no link between relative telomere length and age, we found that birds with longer telomeres arrived earlier for breeding at the colony, and had higher breeding performances (i.e. the amount of time adults managed to maintain their chicks alive, and ultimately breeding success) than individuals with shorter telomeres. Further, we observed a positive correlation between telomere length and natural antibody levels. Taken together, our results add to the growing evidence that telomere length is likely to reflect individual quality difference in wild animal.
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| 5. |
- Mills, James A., et al.
(författare)
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Archiving Primary Data : Solutions for Long-Term Studies
- 2015
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Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 30:10, s. 581-589
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Tidskriftsartikel (refereegranskat)abstract
- The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (PIs) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers.
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| 6. |
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| 7. |
- Patterson, Allison, et al.
(författare)
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Foraging range scales with colony size in high-latitude seabirds
- 2022
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 32:17, s. 3800-3807
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Tidskriftsartikel (refereegranskat)abstract
- Density-dependent prey depletion around breeding colonies has long been considered an important factor controlling the population dynamics of colonial animals.1, 2, 3, 4 Ashmole proposed that as seabird colony size increases, intraspecific competition leads to declines in reproductive success, as breeding adults must spend more time and energy to find prey farther from the colony.1 Seabird colony size often varies over several orders of magnitude within the same species and can include millions of individuals per colony.5,6 As such, colony size likely plays an important role in determining the individual behavior of its members and how the colony interacts with the surrounding environment.6 Using tracking data from murres (Uria spp.), the world’s most densely breeding seabirds, we show that the distribution of foraging-trip distances scales to colony size0.33 during the chick-rearing stage, consistent with Ashmole’s halo theory.1,2 This pattern occurred across colonies varying in size over three orders of magnitude and distributed throughout the North Atlantic region. The strong relationship between colony size and foraging range means that the foraging areas of some colonial species can be estimated from colony sizes, which is more practical to measure over a large geographic scale. Two-thirds of the North Atlantic murre population breed at the 16 largest colonies; by extrapolating the predicted foraging ranges to sites without tracking data, we show that only two of these large colonies have significant coverage as marine protected areas. Our results are an important example of how theoretical models, in this case, Ashmole’s version of central-place-foraging theory, can be applied to inform conservation and management in colonial breeding species.
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| 8. |
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