| 1. |
- Eeva, Tapio, et al.
(författare)
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Experimental manipulation of dietary lead levels in great tit nestlings : limited effects on growth, physiology and survival
- 2014
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Ingår i: Ecotoxicology. - : Springer Science and Business Media LLC. - 0963-9292 .- 1573-3017. ; 23:5, s. 914-928
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Tidskriftsartikel (refereegranskat)abstract
- We manipulated dietary lead (Pb) levels of nestlings in wild populations of the great tit (Parus major L) to find out if environmentally relevant Pb levels would affect some physiological biomarkers (haematocrit [HT], fecal corticosterone metabolites [CORT], heat shock proteins [HSPs], erythrocyte delta-aminolevulinic acid dehydratase activity [ALAd]), growth (body mass, wing length), phenotype (plumage coloration) or survival of nestlings. The responses to three experimental manipulation (control, low and high: 0, 1 and 4 mu g/g body mass/day) are compared with those in a P. major population breeding in the vicinity of a heavy metal source, a copper smelter. Our Pb supplementation was successful in raising the fecal concentrations to the levels found in polluted environments (high: 8.0 mu g/g d.w.). Despite relatively high range of exposure levels we found only few effects on growth rates or physiology. The lack of blood ALAd inhibition suggests that the circulating Pb levels were generally below the toxic level despite that marked accumulation of Pb in femur (high: 27.8 mu g/g d.w.) was observed. Instead, birds in the metal polluted environment around the smelter showed decreased growth rates, lower HT, higher CORT, less colorful plumage and lower survival probabilities than any of the Pb treated groups. These effects are likely related to decreased food quality/quantity for these insectivorous birds at the smelter site. In general, the responses of nestlings to metal exposure and/or associated resource limitation were not gender specific. One of the stress proteins (HSP60), however, was more strongly induced in Pb exposed males and further studies are needed to explore if this was due to higher accumulation of Pb or higher sensitivity of males. In all, our results emphasize the importance of secondary pollution effects (e.g. via food chain disruption) on reproductive output of birds.
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| 2. |
- Eeva, Tapio, et al.
(författare)
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Geographical trends in the yolk carotenoid composition of the pied flycatcher (Ficedula hypoleuca)
- 2011
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 165:2, s. 277-287
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Tidskriftsartikel (refereegranskat)abstract
- Carotenoids in the egg yolks of birds are considered to be important antioxidants and immune stimulants during the rapid growth of embryos. Yolk carotenoid composition is strongly affected by the carotenoid composition of the female's diet at the time of egg formation. Spatial and temporal differences in carotenoid availability may thus be reflected in yolk concentrations. To assess whether yolk carotenoid concentrations or carotenoid profiles show any large-scale geographical trends or differences among habitats, we collected yolk samples from 16 European populations of the pied flycatcher, Ficedula hypoleuca. We found that the concentrations and proportions of lutein and some other xanthophylls in the egg yolks decreased from Central Europe northwards. The most southern population (which is also the one found at the highest altitude) also showed relatively low carotenoid levels. Concentrations of beta-carotene and zeaxanthin did not show any obvious geographical gradients. Egg yolks also contained proportionally more lutein and other xanthophylls in deciduous than in mixed or coniferous habitats. We suggest that latitudinal gradients in lutein and xanthophylls reflect the lower availability of lutein-rich food items in the northern F. hypoleuca populations and in montane southern populations, which start egg-laying earlier relative to tree phenology than the Central European populations. Similarly, among-habitat variation is likely to reflect the better availability of lutein-rich food in deciduous forests. Our study is the first to indicate that the concentration and profile of yolk carotenoids may show large-scale spatial variation among populations in different parts of the species' geographical range. Further studies are needed to test the fitness effects of this geographical variation.
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| 3. |
- Hsu, Bin-Yan, et al.
(författare)
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Transient growth-enhancing effects of elevated maternal thyroid hormones at no apparent oxidative cost during early postnatal period
- 2019
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 50:1
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Tidskriftsartikel (refereegranskat)abstract
- Maternal thyroid hormones (THs) have been proven crucial for embryonic development in humans, but their influence within the natural variation on wild animals remains unknown. So far the only two studies that experimentally investigated the potential fitness consequences of maternal THs in birds found inconsistent results. More studies are thus required to assess the general effects of maternal THs and their influences on more behavioral and physiological parameters. In this study, we experimentally elevated yolk TH content in a wild migratory passerine species, the collared flycatcher Ficedula albicollis, to investigate the effects on hatching success, nestling growth and oxidative stress. We found that TH‐injected eggs had a higher hatching success, and the nestlings hatched from TH‐injected eggs were heavier and larger than control nestlings, but only during the early postnatal period. These differences vanished by fledging. Nestlings from TH‐injected eggs exhibited lower activity of the glutathione‐s‐transferase, a major antioxidant enzyme, than control nestlings at day 12, a few days before fledging, but they did not differ in oxidative damage and overall intracellular oxidative state. These results suggest that the early growth‐enhancing effects incurred no observable oxidative stress. We hypothesize that such a transient growth‐enhancing effect might be adaptive in advancing the development and maturation of the offspring so they are well‐prepared in time for the upcoming migration. Further studies investigating whether such advancing effects can influence long‐term fitness, will be more than valuable.
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| 4. |
- Merilaita, Sami, et al.
(författare)
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Number of eyespots and their intimidating effect on naive predators in the peacock butterfly
- 2011
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 22:6, s. 1326-1331
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Tidskriftsartikel (refereegranskat)abstract
- Predation experiments have shown that the large eyespots (concentric rings of contrasting colors) found on the wings of several lepidopteran species intimidate passerine predators. According to the eye mimicry hypotheses, the intimidation is caused by predators associating the eyespots with the presence (of the eyes) of their own enemy. The conspicuousness hypothesis suggests, instead, that it is simply the conspicuousness of eyespot patterns that is intimidating, possibly due to a sensory bias. We studied how the number of eyespots, 2 or 4, influences intimidation. We predicted that if eye mimicry is important, the maximum response would be reached with a pair of eyespots. On the other hand, if conspicuousness is important, then more than 2 eyespots should result in an even stronger response. The peacock butterfly, Inachis io, has 4 large eyespots on its wings. We presented naive insectivorous birds (pied flycatcher, Ficedula hypoleuca) 2 different prey items made from wings of dead peacock butterflies and a mealworm between the wings. One group of birds received prey that had no or only 2 eyespots visible and the other group received prey that had no or all 4 eyespots visible. Eyespots clearly increased hesitation before attacks. Because the birds were naive, this difference in response to the eyespots was innate. Importantly, there was no difference in attack latency between 2 and 4 eyespots. We conclude that it is unlikely that conspicuousness as such has selected for eyespots in the peacock butterfly.
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| 5. |
- Morales, Judith, et al.
(författare)
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Variation in eggshell traits between geographically distant populations of pied flycatchers Ficedula hypoleuca
- 2013
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Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 44:2, s. 111-120
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Tidskriftsartikel (refereegranskat)abstract
- The expression and impact of maternal effects may vary greatly between populations and environments. However, little is known about large-scale geographical patterns of variation in maternal deposition to eggs. In birds, as in other oviparous animals, the outermost maternal component of an egg is the shell, which protects the embryo, provides essential mineral resources and allows its interaction with the environment in the form of gas exchange. In this study, we explored variation of eggshell traits (mass, thickness, pore density and pigmentation) across 15 pied flycatcher populations at a large geographic scale. We found significant between-population variation in all eggshell traits, except in pore density, suggesting spatial variation in their adaptive benefits or in the females' physiological limitations during egg laying. Between- population variation in shell structure was not due to geographic location (latitude and longitude) or habitat type. However, eggshells were thicker in populations that experienced higher ambient temperature during egg laying. This could be a result of maternal resource allocation to the shell being constrained under low temperatures or of an adaptation to reduce egg water loss under high temperatures. We also found that eggshell colour intensity was positively associated with biliverdin pigment concentration, shell thickness and pore density. To conclude, our findings reveal large- scale between-population variation of eggshell traits, although we found little environmental dependency in their expression. Our findings call for further studies that explore other environmental factors (e.g. calcium availability and pollution levels) and social factors like sexual selection intensity that may account for differences in shell structure between populations.
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| 6. |
- Pitala, Natalia, et al.
(författare)
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The effects of experimentally manipulated yolk androgens on growth and immune function of male and female nestling collared flycatchers Ficedula albicollis
- 2009
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Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 40:2, s. 225-230
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Tidskriftsartikel (refereegranskat)abstract
- Hormone-mediated maternal effects may be an important mechanism for adjusting offspring phenotype to particular requirements of the environment. We manipulated the levels of testosterone and androstenedione in the yolk of collared flycatcher Ficedula albicollis eggs to investigate the effects of pre-natal exposure to androgens on growth and immune function. Androgen treatment tended to reduce the growth of males, and enhance the growth of females, as indicated by significant interaction between sex and androgen treatment. Cellular immune function was not affected by androgen treatment or sex. Survival of nestlings until fledging was not related to androgen treatment. Our results indicate that in the collared flycatcher yolk androgens do not involve clear overall benefits during the nestling stage, and that growth-enhancing effects of increased yolk androgen levels on female nestlings are counterbalanced by detrimental effects on male nestlings.
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| 7. |
- Ruuskanen, Suvi, et al.
(författare)
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Endocrinology of thermoregulation in birds in a changing climate
- 2020
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier BV. - 0303-7207.
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Tidskriftsartikel (refereegranskat)abstract
- The ability to maintain a (relatively) stable body temperature in a wide range of thermal environments by use of endogenous heat production is a unique feature of endotherms such as birds. Endothermy is acquired and regulated via various endocrine and molecular pathways, and ultimately allows wide aerial, aquatic, and terrestrial distribution in variable environments. However, due to our changing climate, birds are faced with potential new challenges for thermoregulation, such as more frequent extreme weather events, lower predictability of climate, and increasing mean temperature. We provide an overview on thermoregulation in birds and its endocrine and molecular mechanisms, pinpointing gaps in current knowledge and recent developments, focusing especially on non-model species to understand the generality of, and variation in, mechanisms. We highlight plasticity of thermoregulation and underlying endocrine regulation, because thorough understanding of plasticity is key to predicting responses to changing environmental conditions. To this end, we discuss how changing climate is likely to affect avian thermoregulation and associated endocrine traits, and how the interplay between these physiological processes may play a role in facilitating or constraining adaptation to a changing climate. We conclude that while the general patterns of endocrine regulation of thermogenesis are quite well understood, at least in poultry, the molecular and endocrine mechanisms that regulate, e.g. mitochondrial function and plasticity of thermoregulation over different time scales (from transgenerational to daily variation), need to be unveiled. Plasticity may ameliorate climate change effects on thermoregulation to some extent, but the increased frequency of extreme weather events, and associated changes in resource availability, may be beyond the scope and/or speed for plastic responses. This could lead to selection for more tolerant phenotypes, if the underlying physiological traits harbour genetic and individual variation for selection to act on – a key question for future research.
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| 8. |
- Ruuskanen, Suvi, et al.
(författare)
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Geographical Variation in Egg Mass and Egg Content in a Passerine Bird
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:11, s. e25360-
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Tidskriftsartikel (refereegranskat)abstract
- Reproductive, phenotypic and life-history traits in many animal and plant taxa show geographic variation, indicating spatial variation in selection regimes. Maternal deposition to avian eggs, such as hormones, antibodies and antioxidants, critically affect development of the offspring, with long-lasting effects on the phenotype and fitness. Little is however known about large-scale geographical patterns of variation in maternal deposition to eggs. We studied geographical variation in egg components of a passerine bird, the pied flycatcher (Ficedula hypoleuca), by collecting samples from 16 populations and measuring egg and yolk mass, albumen lysozyme activity, yolk immunoglobulins, yolk androgens and yolk total carotenoids. We found significant variation among populations in most egg components, but ca. 90% of the variation was among individuals within populations. Population however explained 40% of the variation in carotenoid levels. In contrast to our hypothesis, we found geographical trends only in carotenoids, but not in any of the other egg components. Our results thus suggest high within-population variation and leave little scope for local adaptation and genetic differentiation in deposition of different egg components. The role of these maternally-derived resources in evolutionary change should be further investigated.
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| 9. |
- Ruuskanen, Suvi, et al.
(författare)
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Large-scale geographical variation in eggshell metal and calcium content in a passerine bird (Ficedula hypoleuca)
- 2014
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 21:5, s. 3304-3317
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Tidskriftsartikel (refereegranskat)abstract
- Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We studied large-scale geographic variation in metal levels in the eggs of a small passerine, the pied flycatcher (Ficedula hypoleuca), sampled from 15 populations across Europe. We measured 10 eggshell elements (As, Cd, Cr, Cu, Ni, Pb, Zn, Se, Sr, and Ca) and several shell characteristics (mass, thickness, porosity, and color). We found significant variation among populations in eggshell metal levels for all metals except copper. Eggshell lead, zinc, and chromium levels decreased from central Europe to the north, in line with the gradient in pollution levels over Europe, thus suggesting that eggshell can be used as an indicator of pollution levels. Eggshell lead levels were also correlated with soil lead levels and pH. Most of the metals were not correlated with eggshell characteristics, with the exception of shell mass, or with breeding success, which may suggest that birds can cope well with the current background exposure levels across Europe.
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| 10. |
- Ruuskanen, Suvi, et al.
(författare)
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Long-term effects of yolk androgens on phenotype and parental feeding behavior in a wild passerine
- 2012
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 66:9, s. 1201-1211
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Tidskriftsartikel (refereegranskat)abstract
- Early growth conditions, such as exposure to maternally derived androgens in bird eggs, have been shown to shape offspring in ways that may have important long-term consequences for phenotype and behavior. Using an experimental approach, we studied the long-term effects of yolk androgens on several phenotypic traits and parental behavior in adult and female collared flycatchers (Ficedula albicollis). We elevated yolk androgen levels and monitored the experimental recruits the following breeding seasons. Androgen treatment had a sex-dependent effect on adult body condition, yolk androgen-treated males being heavier than control males when controlling for size, a result which may be caused potentially by selective mortality, physiological differences, or different life-history strategies. Androgen treatment did not however affect the expression of sexually selected plumage ornaments (forehead and wing patch size), UV coloration, or parental feeding rate in either sex. Our results suggest that yolk androgens are unlikely to affect sexual selection via plumage characteristics or contribute to breeding success via altered parental care. Yolk androgens do not seem to act as a means for female collared flycatchers to enhance the attractiveness of their sons. The lower return rate previously observed for androgen-treated male offspring compared to controls may therefore not be due to lower mating or breeding success, but may rather reflect lower survival or higher dispersal propensity of yolk androgen-treated males.
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| 11. |
- Ruuskanen, Suvi, et al.
(författare)
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Long-term fitness consequences of high yolk androgen levels : sons pay the costs
- 2012
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 26:4, s. 884-894
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Tidskriftsartikel (refereegranskat)abstract
- 1. Early growth conditions, for example hormonal environment during embryonic development, may have long-lasting effects on behaviour and phenotype, with subsequent fitness consequences. Yolk androgens have been shown to affect various offspring traits in the short-term, but fitness consequences for either offspring or parents, a prerequisite for studying the adaptiveness of this maternal effect, are poorly known in the wild. 2. We experimentally elevated yolk androgen levels of whole clutches in a wild population of collared flycatchers (Ficedula albicollis) and investigated the long-term effects of yolk androgens on offspring local recruitment, parental return rate, and timing and success of breeding in both parents and offspring in the breeding season(s) following the manipulation. 3. Yolk androgen elevation lowered the local recruitment rate of male, but not female offspring, but had no effect on any breeding parameters of offspring of either sex. Furthermore, yolk androgen elevation of the clutch had no effect on the return rate or any breeding parameters of the parents. 4. Our results indicate that high yolk androgen levels may impose a potential direct fitness cost for male offspring, but no long-lasting additional indirect fitness costs for parents (direct costs of transferring androgens to eggs not considered). Such a sex-specific cost on offspring could constrain yolk androgen deposition and select for sex-specific deposition mechanisms. 5. As yolk androgen levels in this population are heritable, our results on long-term fitness effect of yolk androgens support the idea that hormone-mediated maternal effects may evolve under selection and thereby affect evolutionary processes.
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| 12. |
- Ruuskanen, Suvi, et al.
(författare)
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Yolk androgens do not appear to mediate sexual conflict over parental investment in the collared flycatcher Ficedula albicollis
- 2009
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 55:4, s. 514-519
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Tidskriftsartikel (refereegranskat)abstract
- Mates and females are in conflict over parental care, as it would be favourable for one parent to shift labour to the other. Yolk hormones may offer a mechanism through which female birds could influence offspring traits in ways that increase the relative investment by the male. We studied the role of yolk androgens in mediating sexual conflict over parental care in the collared flycatcher (Ficedula albicollis). In a cross-fostering experiment, the male's proportion of total feeding visits increased with increasing androgen levels in the foster eggs. This could suggest that sexual conflict over parental care may be influenced by the female's differential allocation of yolk androgens or a maternal effect associated with yolk androgens. However, when we experimentally elevated yolk androgen levels, male feeding rates did not differ between control and androgen-manipulated nests. This suggests that other egg components correlated with yolk androgen levels, rather than yolk androgen levels per se, may influence male parental effort. In conclusion, yolk androgens per se do not appear to mediate sexual conflict over parental investment in the collared flycatcher. (C) 2009 Elsevier Inc. All rights reserved.
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| 13. |
- Stier, Antoine, et al.
(författare)
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Born to be young? : Prenatal thyroid hormones increase early-life telomere length in wild collared flycatchers
- 2020
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Ingår i: Biology Letters. - : ROYAL SOC. - 1744-9561 .- 1744-957X. ; 16:11
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Tidskriftsartikel (refereegranskat)abstract
- The underlying mechanisms of the lifelong consequences of prenatal environmental condition on health and ageing remain little understood. Thyroid hormones (THs) are important regulators of embryogenesis, transferred from the mother to the embryo. Since prenatal THs can accelerate early-life development, we hypothesized that this might occur at the expense of resource allocation in somatic maintenance processes, leading to premature ageing. Therefore, we investigated the consequences of prenatal TH supplementation on potential hallmarks of ageing in a free-living avian model in which we previously demonstrated that experimentally elevated prenatal TH exposure accelerates early-life growth. Using cross-sectional sampling, we first report that mitochondrial DNA (mtDNA) copy number and telomere length significantly decrease from early-life to late adulthood, thus suggesting that these two molecular markers could be hallmarks of ageing in our wild bird model. Elevated prenatal THs had no effect on mtDNA copy number but counterintuitively increased telomere length both soon after birth and at the end of the growth period (equivalent to offsetting ca 4 years of post-growth telomere shortening). These findings suggest that prenatal THs might have a role in setting the 'biological' age at birth, but raise questions about the nature of the evolutionary costs of prenatal exposure to high TH levels.
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| 14. |
- Taborsky, Barbara, et al.
(författare)
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An evolutionary perspective on stress responses, damage and repair
- 2022
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Variation in stress responses has been investigated in relation to environmental factors, species ecology, life history and fitness. Moreover, mechanistic studies have unravelled molecular mechanisms of how acute and chronic stress responses cause physiological impacts (‘damage’), and how this damage can be repaired. However, it is not yet understood how the fitness effects of damage and repair influence stress response evolution. Here we study the evolution of hormone levels as a function of stressor occurrence, damage and the efficiency of repair. We hypothesise that the evolution of stress responses depends on the fitness consequences of damage and the ability to repair that damage. To obtain some general insights, we model a simplified scenario in which an organism repeatedly encounters a stressor with a certain frequency and predictability (temporal autocorrelation). The organism can defend itself by mounting a stress response (elevated hormone level), but this causes damage that takes time to repair. We identify optimal strategies in this scenario and then investigate how those strategies respond to acute and chronic exposures to the stressor. We find that for higher repair rates, baseline and peak hormone levels are higher. This typically means that the organism experiences higher levels of damage, which it can afford because that damage is repaired more quickly, but for very high repair rates the damage does not build up. With increasing predictability of the stressor, stress responses are sustained for longer, because the animal expects the stressor to persist, and thus damage builds up. This can result in very high (and potentially fatal) levels of damage when organisms are exposed to chronic stressors to which they are not evolutionarily adapted. Overall, our results highlight that at least three factors need to be considered jointly to advance our understanding of how stress physiology has evolved: (i) temporal dynamics of stressor occurrence; (ii) relative mortality risk imposed by the stressor itself versus damage caused by the stress response; and (iii) the efficiency of repair mechanisms.
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| 15. |
- Taborsky, Barbara, et al.
(författare)
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Towards an Evolutionary Theory of Stress Responses
- 2021
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Ingår i: Trends in Ecology & Evolution. - : Elsevier BV. - 0169-5347 .- 1872-8383. ; 36:1, s. 39-48
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Forskningsöversikt (refereegranskat)abstract
- All organisms have a stress response system to cope with environmental threats, yet its precise form varies hugely within and across individuals, populations, and species. While the physiological mechanisms are increasingly understood, how stress responses have evolved remains elusive. Here, we show that important insights can be gained from models that incorporate physiological mechanisms within an evolutionary optimality analysis (the 'evo-mecho' approach). Our approach reveals environmental predictability and physiological constraints as key factors shaping stress response evolution, generating testable predictions about variation across species and contexts. We call for an integrated research programme combining theory, experimental evolution, and comparative analysis to advance scientific understanding of how this core physiological system has evolved.
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| 16. |
- Thoral, Elisa, et al.
(författare)
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The relationship between mitochondrial respiration, resting metabolic rate and blood cell count in great tits
- 2024
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Ingår i: Biology Open. - 2046-6390. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Although mitochondrial respiration is believed to explain a substantial part of the variation in resting metabolic rate (RMR), few studies have empirically studied the relationship between organismal and cellular metabolism. We therefore investigated the relationship between RMR and mitochondrial respiration of permeabilized blood cells in wild great tits (Parus major L.). We also studied the correlation between mitochondrial respiration traits and blood cell count, as normalizing mitochondrial respiration by the cell count is a method commonly used to study blood metabolism. In contrast to previous studies, our results show that there was no relationship between RMR and mitochondrial respiration in intact blood cells (i.e. with the ROUTINE respiration). However, when cells were permeabilized and interrelation re-assessed under saturating substrate availability, we found that RMR was positively related to phosphorylating respiration rates through complexes I and II (i.e. OXPHOS respiration) and to the mitochondrial efficiency to produce energy (i.e. net phosphorylation efficiency), though variation explained by the models was low (i.e. linear model: R2=0.14 to 0.21). However, unlike studies in mammals, LEAK respiration without [i.e. L(n)] and with [i.e. L(Omy)] adenylates was not significantly related to RMR. These results suggest that phosphorylating respiration in blood cells can potentially be used to predict RMR in wild birds, but that this relationship may have to be addressed in standardized conditions (permeabilized cells) and that the prediction risks being imprecise. We also showed that, in our conditions, there was no relationship between any mitochondrial respiration trait and blood cell count. Hence, we caution against normalising respiration rates using this parameter as is sometimes done. Future work should address the functional explanations for the observed relationships, and determine why these appear labile across space, time, taxon, and physiological state.
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