| 1. |
- Bell, Alison M., et al.
(författare)
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Variable neuroendocrine responses to ecologically-relevant challenges in sticklebacks
- 2007
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 91:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- Variable neuroendocrine responses to ecologically-relevant challenges in sticklebacks. PHYSIOL BEHAV 00(0) 000-000, 2006. Here, we compare the behavioral, endocrine and neuroendocrine responses of individual sticklebacks exposed to either an unfamiliar conspecific or to a predator. We found that the two stressors elicited a similar hypothalamic–pituitary–interrenal response as assessed by whole-body concentrations of cortisol, but produced quite different patterns of change in brain monoamine and monoamine metabolite content as assessed by concentrations of serotonin (5-HT), dopamine (DA), norepinephrine (NE) and the monoamine metabolites 5-hydroxyindole acetic acid (5-HIAA), homovanillic acid (HVA) and 3-4-dihydroxyphenylacetic acid (DOPAC). For example, relative to baseline levels, NE levels were elevated in individuals exposed to a predator but were lower in individuals confronted by a challenging conspecific. Levels of monoamine neurotransmitters in specific regions of the brain showed extremely close links with behavioral characteristics. Frequency of attacking a conspecific and inspecting a predator were both positively correlated with concentrations of NE. However, whereas serotonin was negatively correlated with frequency of attacking a conspecific, it was positively associated with predator inspection. The data indicate that the qualitative and quantitative nature of the neuroendocrine stress response of sticklebacks varies according to the nature of the stressor, and that interindividual variation in behavioural responses to challenge are reflected by neuroendocrine differences.
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| 2. |
- Berglund, Anders, et al.
(författare)
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Female-female competition over reproduction
- 1993
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 4:2, s. 184-187
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Brick, Olle, 1962-
(författare)
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Risk assessment and contest behaviour in the Cichlid fish Nannacara anomala
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The risk of predation is an important factor for our understanding of animal behaviour in general. This thesis investigates the influence of predation risk on fighting behaviour in the cichlid fish Nannacara anomala. According to game theoretical models, a fighting animal should base its decisions during a fight on its fighting ability in relation to the opponent and on the value of the contested resource. The result of the present thesis suggests that fighting N. anomala males engaged in escalated fighting are likely to be vulnerable to predation due to impaired vigilance. The presence of a model fish predator made the males reluctant to perform mouth wrestling and the intensity of mouth wrestling decreased significantly compared to undisturbed fights. When I used predation risk as a cost of fighting, the variability among fights increased. In some fights, the use of low intensity behaviour elements increased in the presence of a model fish predator in accordance with the previous findings on vigilance. Other fights escalated to mouth wrestling in a way resembling undisturbed fights, suggesting a difference among contestants in what behaviour they prefer to use when there is an increased risk of predation. The study showed that fish classified as 'bold' towards a model fish predator escalated significantly faster to mouth wrestling and performed significantly more agonistic behaviour in the presence of a model fish predator compared with fish that had been classified as 'cautious'. 'Bold' pairs also escalated significantly faster to mouth wrestling compared to 'cautious' pairs when the model fish predator was absent. In agreement with theoretical predictions, fights between N. anomala males contained significantly more costly behavioural acts in the presence of a female compared to fights in the absence of a female. Despite the presence of a female, the variability among fights increased significantly when predation risk increased, suggesting that increased risk of predation is not accepted even in fights about a valuable resource in this species. The study also showed that the probability for the lighter fish to win increased in the presence of a female and when predation risk was high. In fights over a valuable resource, other asymmetries besides relative body weight are likely to become important and increased risk of predation may impair assessment of relative fighting ability or the contestants may differ in risk assessment. A difference among contestants in what behaviour they prefer to use, clearly expressed when predation risk increase, may be an additional factor explaining some of the variability among fights found in many studies.
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| 4. |
- Cubitt, K. Fiona, et al.
(författare)
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Social hierarchies, growth and brain serotonin metabolism in Atlantic salmon (Salmo salar) kept under commercial rearing conditions
- 2008
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 94:4, s. 529-535
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring social interactions between individuals in large, high-density groups poses several challenges. Here we demonstrate that relative concentrations of serotonin (5-Hydroxytryptamine, 5-HT) and its principal catabolite 5-Hydroxyindoleacetic acid (5-HIAA) in brain tissue of individual fish reflect social organisation in large groups of farmed Atlantic salmon. In the central nervous system of vertebrates, the monoamine neurotransmitter/neuromodulator 5-HT is critical for maintaining adaptive physiological, cognitive and emotional processes. In both teleost fish and mammals it has previously been shown that social interactions in small groups lead to elevated 5-HT release and/or metabolism in subordinate individuals, as indicated by the 5-HIAA/5-HT concentration ratio. In the current study, evidence is presented of non-linear dominance hierarchies in farmed Atlantic salmon (Salmo salar) kept at high rearing densities. The physiological effect of these hierarchies was decreased when food resources were abundant, although some subordinate fish still showed altered brain serotonergic activity and failed to grow even feed was available in excess. The largest effect of decreased feed rations was seen in fish of intermediate size, where competition appeared to increase with reduced access to feed. The largest individuals in each rearing unit showed low 5-HIAA/5-HT ratios independent of feeding regime. A novel observation, with respect to previous studies, was that elevated brain 5-HIAA/5-HT ratios resulted from decreased 5-HT concentrations rather than elevated 5-HIAA in small fish. Thus, in light of the serotonin deficit hypothesis of depression, it cannot be excluded that social stress is important for animal welfare even in large, relatively homogenous groups of animals reared in captivity.
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| 5. |
- Dahl, Emma
(författare)
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Physiological and Environmental Processes Influencing Growth Strategies in Amphibian Larvae
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cost and benefits of high individual growth rates are likely to vary across different environments leading to geographic differentiation in growth strategies. In ectotherms, habitats constrained by short growing seasons favour rapid growth and development leading to adaptive latitudinal clines in these traits. Geographic variation in growth strategies should be influenced by physiological variation as well as environmental factors, however many of these mechanisms remain largely unexplored. In my thesis, I studied hormonal correlates of growth strategies, and compensatory responses to phenological variation and environmental stress in anuran tadpoles. I tested the hypotheses that fast growing high latitude common frog Rana temporaria tadpoles have higher growth hormone (GH) expression, and low stress hormone (CORT) elevation in response to predator stress. I found no relationship between GH expression and latitude, but CORT response decreased with latitude after 24 hours of predator exposure. Lower CORT response at high latitude can be adaptive as it may enable the tadpoles to maintain high growth in time constrained habitats. I also found that breeding phenology affected latitudinal variation in growth, development and anti-predator strategies. Northern R. temporaria tadpoles were phenotypically more similar to southern tadpoles when breeding occurred early, suggesting that part of the latitudinal variation is plastic and affected by yearly variation in phenology. When time stress was manipulated by delaying hatching, tadpoles were able to compensate by increasing their development and growth during the larval stage, decreasing the cost of the delayed development. In the final study, I found that northern tadpoles showed stronger compensatory growth during the larval stage than southern tadpoles after being delayed by low food, however, temperature manipulation did not induce differences in the compensatory responses. In general, my results highlight the roles of both environmental and genetic variation in determining individual growth strategies.
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| 6. |
- Lans, Linnea, 1975-
(författare)
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Behaviour and metabolic rates of brown trout and Atlantic salmon : Influence of food, environment and social interactions
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For Atlantic salmon (Salmo salar) and brown trout (Salmo trutta), the decision to migrate or when to migrate is believed to be influenced by the individual’s metabolic rate (MR) relative its food intake. As MR was expected to be related to behaviour, the potential links between behaviour and metabolic costs was studied. For both salmon and trout the dominant individual had a higher standard metabolic rate (SMR) than its subordinate counterpart. Also, successful migrants of brown trout had a higher SMR than unsuccessful migrants, whereas no such difference was found for obligate migratory Atlantic salmon. Measures of variation in MR and boldness indicated that Atlantic salmon was more sensitive to stress than brown trout and became passive when stressed. When two trout were interacting, an increase in ventilation rate (VR) was positively correlated to fighting intensity. The first day after an interaction, VR did not differ between small dominant and subordinate trout (mean size 3.7g), whereas for large trout (26.0g) subordinates had higher VR than dominants. However, a combination of low temperature (10°C) and high water velocity (22cm/s) eliminated this difference. This probably reflects the high swimming activity of small dominants and the low motivation for dominants to defend a large territory when temperatures were low and the cost of moving was high. These results show that the relationship between MR and behaviour may differ depending on species, fish size and environmental factors.
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| 7. |
- Robinson-Wolrath, Sarah, 1979-
(författare)
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Morphological and Behavioural Differentiation in a Pipefish
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A central goal of evolutionary biology is to understand the processes responsible for morphological, genetic and behavioural differentiation between sexes and among geographically distinct populations. Perhaps the most significant processes are genetic drift, natural selection, phenotypic plasticity and sexual selection. The main aim of this thesis was to investigate differentiation among individuals and populations of the sex-role reversed pipefish (Syngnathus typhle) and, consequently, determine which processes may be responsible for emerging patterns. This unique species is characterised by males predominately choosing amongst displaying females.In this thesis I revealed, on a microgeographic scale, morphological differentiation without genetic divergence among populations. Interestingly, females differed in size whereas the males did not. For females in this sex-role reversed species, the costs of expressing a plastic phenotype may be outweighed by the potential gains from greater survivorship, higher fecundity or increased mating success. Thus, females gain the ability to make themselves as conspicuous and attractive to males as possible in the specific environment they are living. Moreover, behavioural experiments, which focussed on describing “personalities”, reproductive investment strategies, and mate-sampling tactics, also indicated that males as well as females had the behavioural plasticity required to adjust to the environment in which they live. To this end, using video playbacks as experimental stimuli may be especially rewarding in this species.Overall, the studies in this thesis acknowledge the ability of species to fine-tune their phenotype to maximise fitness and, therefore, highlight the importance of considering patterns of differentiation in an environment-specific context.
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| 8. |
- Ruiz-Gomez, Maria de Lourdes, et al.
(författare)
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Behavioral plasticity in rainbow trout (Oncorhynchus mykiss) with divergent coping styles : when doves become hawks
- 2008
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 54:4, s. 534-8
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Tidskriftsartikel (refereegranskat)abstract
- Consistent and heritable individual differences in reaction to challenges, often referred to as stress coping styles, have been extensively documented in vertebrates. In fish, selection for divergent post-stress plasma cortisol levels in rainbow trout (Oncorhynchus mykiss) has yielded a low (LR) and a high responsive (HR) strain. A suite of behavioural traits is associated with this physiological difference, with LR (proactive) fish feeding more rapidly after transfer to a new environment and being socially dominant over HR (reactive) fish. Following transport from the UK to Norway, a switch in behavioural profile occurred in trout from the 3rd generation; HR fish regained feeding sooner than LR fish in a novel environment and became dominant in size-matched HR-LR pairs. One year after transport, HR fish still fed sooner, but no difference in social dominance was found. Among offspring of transported fish, no differences in feeding were observed, but as in pre-transported 3rd generation fish, HR fish lost fights for social dominance against size-matched LR opponents. Transported fish and their offspring retained their distinctive physiological profile throughout the study; HR fish showed consistently higher post-stress cortisol levels at all sampling points. Altered risk-taking and social dominance immediately after transport may be explained by the fact that HR fish lost more body mass during transport than did LR fish. These data demonstrate that some behavioural components of stress coping styles can be modified by experience, whereas behavioural plasticity is limited by genetic effects determining social position early in life story.
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| 9. |
- Schjolden, Joachim, 1971-
(författare)
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Stress Coping Strategies in Rainbow Trout (Oncorhynchus mykiss)
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Animals show a great variety in physiological and behavioural responses to stressors. These responses are often bimodally distributed within populations and show consistency on an individual level over time and across situations, which in terrestrial vertebrates have been identified as proactive and reactive stress coping strategies. Proactive animals show lower cortisol responses, higher sympathetic activation and brain serotonergic activity compared to reactive animals. Behaviourally, proactive animals are more aggressive, more active in avoiding stressors, they form routines and show fewer cases of conditioned immobility compared to reactive animals. Our aim has been to reveal if such stress coping strategies exist in fish. Our results show that rainbow trout with high (HR) or low (LR) cortisol responses to stressors differs in sympathetic activation and brain serotonin turnover in the same manner as proactive and reactive mammals. HR fish showed less locomotor activity when reared in large groups (30 individuals) compared to LR fish. When reared in isolation there were no differences between HR and LR fish when exposed to stressors within a familiar environment. The adaption of a proactive coping style among reactive coping individuals when they are challenged within a familiar environment has previously been shown to be distinction between proactive and reactive coping mammals. However, when they were transferred to unfamiliar environments a behavioural difference between the two lines was observed indicating different stress coping strategies akin to those described in mammals. Finally, we observed a consistency over time in the cortisol response of an unselected line of rainbow trout. Fish from this line also demonstrated a correlation between behavioural responses to different stressors. However, there was no apparent connection between these behavioural responses and the cortisol response. Overall, the results of this thesis have strengthened the hypothesis that different stress coping strategies exist in teleost fish.
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