| 1. |
- Ellis, Vincenzo A., et al.
(författare)
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Explaining prevalence, diversity and host specificity in a community of avian haemosporidian parasites
- 2020
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 129:9, s. 1314-1329
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Tidskriftsartikel (refereegranskat)abstract
- Many hypotheses attempt to explain parasite–host associations, but rarely are they examined together in a single community. For hosts, key traits are the proportion of infected individuals (prevalence) and the diversity of parasites infecting them. A key parasite trait is host specificity, ranging from specialists infecting one or a few closely related species to generalists infecting many species. We tested 10 hypotheses to explain host-parasite associations; five ‘host-centric’ (e.g. prevalence is related to host abundance) and five ‘parasite-centric’ (e.g. parasite abundance is related to host specificity). We analyzed a community of 67 locally transmitted avian haemosporidian parasite lineages (genera Plasmodium, Haemoproteus or Leucocytozoon), sampled from 2726 birds (64 species) in southern Sweden. Among host-centric hypotheses, Haemoproteus and Leucocytozoon prevalence and Haemoproteus diversity were related to host habitat preferences, whereas there were no relationships with host abundance or body mass. Haemoproteus and Leucocytozoon prevalences were more similar among closely related than among distantly related host species. Haemoproteus prevalence and diversity were lower in host species with few close relatives (‘evolutionarily distinct’ hosts). Among parasite-centric hypotheses, most lineages, even relative generalists, infected closely related host species more often than expected by chance. However, the host species of Haemoproteus and Leucocytozoon lineages overlapped less among lineages than expected by chance. Specialists did not reach higher prevalences than generalists on single host species. However, the abundance of Haemoproteus lineages was related to host specificity with generalists more common than specialists; this was driven by three closely related generalists. Host specificity of parasites was unrelated to the abundance or evolutionarily distinctiveness of their hosts. Parasite communities are likely structured by many factors and cannot be explained by hypotheses focusing solely on hosts or parasites. However, we found consistent effects of host phylogenetic relationships, plausibly a result of evolutionarily conserved host immune systems limiting parasite distributions.
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| 2. |
- Nilsson, Johan F., et al.
(författare)
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Predictability of food supply modulates nocturnal hypothermia in a small passerine : Food supply and nocturnal hypothermia
- 2020
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Ingår i: Biology letters. - 1744-9561. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great tits Parus major. A 'predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally 'unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.
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| 3. |
- Nilsson, Johan, et al.
(författare)
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Predictability of food supply modulates nocturnal hypothermia in a small passerine
- 2020
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Ingår i: Biology letters. - : The Royal Society. - 1744-957X .- 1744-9561. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- The combination of short days and long cold winter nights, in temperate regions, presents a major challenge for small diurnal birds. Small birds regularly employ heterothermy and enter rest-phase hypothermia during winter nights to conserve energy. However, we know little about how environmental conditions, such as food availability, shape these strategies. We experimentally manipulated food availability in winter to free-living great titsParus major. A ‘predictable' and constant food supply was provided to birds in one area of a forest, while birds in another area did not have access to a reliable supplementary food source. We found that predictability of food affected the extent of nocturnal hypothermia, but the response differed between the sexes. Whereas male nocturnal body temperature was similar regardless of food availability, females exposed to a naturally ‘unpredictable' food supply entered deeper hypothermia at night, compared with females that had access to predictable food and compared with males in both treatment groups. We suggest that this response is likely a consequence of dominance, and subdominant females subject to unpredictable food resources cannot maintain sufficient energy intake, resulting in a higher demand for energy conservation at night.
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| 4. |
- Pape Møller, Anders, et al.
(författare)
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Interaction of climate change with effects of conspecific and heterospecific density on reproduction
- 2020
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 129:12, s. 1807-1819
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Tidskriftsartikel (refereegranskat)abstract
- We studied the relationship between temperature and the coexistence of great tit Parus major and blue tit Cyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density‐dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.
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| 5. |
- Andersson, Bengt-Åke, et al.
(författare)
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Impact of Cigarette Smoking and Head and Neck Squamous Cell Carcinoma on Circulating Inflammatory Biomarkers
- 2020
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Ingår i: Oncology. - : S. Karger. - 0030-2414 .- 1423-0232. ; 98:1, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Smoking induces inflammation and an immune response. A cancer-related inflammatory response has been seen in smoking and nonsmoking head and neck squamous cell carcinoma (HNSCC) patients.OBJECTIVES: The aim of this study was to analyze the possible separated effects of smoking or HNSCC on 18 inflammatory or immune regulatory biomarkers.METHODS: Fifty-one nonsmoking and 36 smoking pretreated HNSCC patients and 101 nonsmoking and 39 smoking controls were included in this study. The levels of 18 inflammatory or immune regulatory biomarkers were analyzed. A multivariable linear regression model was used to predict the impact of smoking and HNSCC on the levels of the biomarkers.RESULTS: Smoking had the highest impact on total WBC, IFN-γ, and MCP-1 levels. The highest impact of HNSCC was found on neutrophils, neutrophil-to-lymphocyte ratio, HsCRP, MIP-1b, and TNF-α levels.CONCLUSION: Identifying HNSCC or smoking-related inflammatory biomarkers might contribute to the understanding of the immune response in HNSCC patients. This study could provide information of inflammatory biomarkers in HNSCC patients.
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| 6. |
- Andreasson, Fredrik, et al.
(författare)
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Age differences in night-time metabolic rate and body temperature in a small passerine
- 2020
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Ingår i: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology. - : Springer Science and Business Media LLC. - 0174-1578. ; 190, s. 349-359
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Tidskriftsartikel (refereegranskat)abstract
- Spending the winter in northern climes with short days and cold ambient temperatures (Ta) can be energetically challenging for small birds that have high metabolic and heat loss rates. Hence, maintaining body temperature (Tb) in Ta below thermoneutrality can be energetically costly for a small bird. We still know little about how increased heat production below thermoneutrality affects the level at which Tb is maintained, and if these patterns are age specific. To test this, we measured subcutaneous body temperature (Ts) and resting metabolic rate (RMR) simultaneously in blue tits (Cyanistes caeruleus) during winter nights in Ta’s ranging from 25 to − 15 °C. RMR increased below the lower critical temperature (LCT, estimated at 14 °C) and was 6% higher in young (birds in their first winter) compared to old birds (birds in their second winter or older). The higher RMR was also mirrored in higher Ts and thermal conductance (C) in young birds, which we suggest could be caused by age differences in plumage quality, likely driven by time constraints during moult. Reduction in nightly predicted Tb was modest and increased again at the coldest ambient temperatures, suggesting that either heat retention or heat production (or both) improved when Ta reached levels which are cold by the standards of birds in our population. Our results show that levels of heat production and Tb can be age specific. Further studies should address age-specific differences on quality, structure, and thermal conductivity of plumage more explicitly, to investigate the role of variation in insulation in age-linked metabolic phenotypes.
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| 7. |
- Andreasson, Fredrik, et al.
(författare)
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Avian Reproduction in a Warming World
- 2020
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Weather influences both the distribution and life-history strategies of birds. Temperature ranks amongst the more important weather parameters in this regard since warming springs in temperate and high latitudes and more frequent heat-waves globally have caused major changes in breeding phenology and negatively affected adult and juvenile survival, respectively. Both long-term and stochastic changes in temperature can have fundamental consequences for avian reproduction even when the effects are not lethal, such as via thermal constraints on parental provisioning and chick growth. To date, most of what we know about temperature effects on nestling development and parental effort during reproduction is based on correlative data. In addition, an increasing amount of evidence indicates that temperature change also significantly affects birds that breed in cooler temperate areas, which so far has been somewhat overlooked. Therefore, in this perspective piece, we outline the existing literature on temperature effects on nestling development and parental behavior, with an emphasis on what needs to be done to address the causal effects of temperature change on avian reproduction under climate change. We finish by providing an outlook over future avenues of research, and give suggestions of some specific areas that might be especially promising in developing this field of research.
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| 8. |
- Andreasson, Fredrik, et al.
(författare)
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Body temperature responses of Great Tits Parus major to handling in the cold
- 2020
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Ingår i: Ibis. - : Wiley. - 0019-1019 .- 1474-919X. ; 162:3, s. 836-844
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Tidskriftsartikel (refereegranskat)abstract
- Animals typically respond to stressful stimuli such as handling by increasing core body temperature. However, small birds in cold environments have been found to decrease body temperature (Tb) when handled over longer periods, although there are no data extending beyond the actual handling event in such birds. We therefore measured both the initial Tb decrease during ringing and standardized Tb sampling, and subsequent recovery of Tb after this handling protocol in wild Great Tits Parus major roosting in nestboxes in winter. Birds reduced their Tb by 2.3 °C during c. 4 min of handling. When birds were returned to their nestboxes after handling, Tb decreased by a further 1.9 °C over c. 2 min, reaching a Tb of 34.6 °C before taking 20 min to rewarm to 2.5 °C above their initial Tb. The Tb reduction during handling could be a consequence of increased heat loss rate from disrupted plumage insulation, whereas Tb reduction after handling might reflect reduced heat production. These are important factors to consider when handling small birds in the cold.
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| 9. |
- Andreasson, Fredrik, et al.
(författare)
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Experimental facilitation of heat loss affects work rate and innate immune function in a breeding passerine bird
- 2020
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 223:8
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Tidskriftsartikel (refereegranskat)abstract
- The capacity to get rid of excess heat produced during hard work is a possible constraint on parental effort during reproduction [heat dissipation limit (HDL) theory]. We released hard-working blue tits (Cyanistes caeruleus) from this constraint by experimentally removing ventral plumage. We then assessed whether this changed their reproductive effort (feeding rate and nestling size) and levels of self-maintenance (change in body mass and innate immune function). Feather-clipped females reduced the number of feeding visits and increased levels of constitutive innate immunity compared with unclipped females but did not fledge smaller nestlings. Thus, they increased self-maintenance without compromising current reproductive output. In contrast, feather clipping did not affect the number of feeding visits or innate immune function in males, despite increased heat loss rate. Our results show that analyses of physiological parameters, such as constitutive innate immune function, can be important when trying to understand sources of variation in investment in self-maintenance versus reproductive effort and that risk of overheating can influence innate immune function during reproduction.
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| 10. |
- Bergman, Erika, et al.
(författare)
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Time trends in pediatric fractures in a Swedish city from 1950 to 2016
- 2020
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 91:5, s. 598-604
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose — As previous studies indicate time trends in pediatric fracture incidence, we followed the incidence in a Swedish city between 1950 and 2016. Patients and methods — Malmö city, Sweden had 322,574 inhabitants in 2015. We used diagnosis registry, charts, and radiographs of the only city hospital to classify fractures in individuals < 16 years in 2014–2016, and compared these with data from 1950–2006. We used joinpoint regression to analyze time trends and present results as mean annual percentage changes (APC). Differences between periods are described as incident rate ratios (IRR). To describe uncertainty, 95% confidence intervals (CI) are used. Results — During 2014–2016 the pediatric fracture incidence was 1,786 per 105 person-years (boys 2,135 and girls 1,423). From 1950 onwards age-adjusted fracture incidence increased until 1979 in both boys (APC +1.5%, CI 1.2–1.8) and girls (APC +1.6%, CI 0.8–2.5). The incidence remained stable from 1979 to 2016 (APC in boys 0.0%, CI –0.3 to 0.3 and in girls –0.2%, CI –1.1 to 0.7). Age-adjusted incidence 2014–2016 was higher than 2005–2006 in girls (IRR 1.1, CI 1.03–1.3), but not in boys (IRR 1.0, CI 0.9–1.1). Interpretation — Fracture incidence was in girls higher in 2014–2016 than in 2005–2006. However, only with more than 2 measuring points are meaningful trend analyses possible. When we analyzed the period 1950–2016 with 17 measuring points and joinpoint regression, we found that fracture incidence increased in both sexes until 1979 but has thereafter been stable.
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