Telomere dynamics in wild brown trout: effects of compensatory growth and early growth investment

Näslund, Joacim; Pauliny, Angela; Blomqvist, Donald; Johnsson, Jörgen I.

doi:10.1007/s00442-015-3263-0

Cited by 42 publications

(45 citation statements)

References 47 publications

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“…However, the above-stated general predictions regarding low-asset individuals apply to LL and HL, in relation to HH. Compensatory growth, predicted for LH, has been observed repeatedly in older juveniles of brown trout from the same population as used in this study (Johnsson and Bohlin 2006; Sundström et al 2013; Näslund et al 2015). Alternatively, SDS resulting from increased size may result in a general tendency for trout fry to maximize activity, neophobia, and aggression regardless of energetic state.…”

Section: Introductionsupporting

confidence: 55%

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Näslund

Johnsson

2016

Behav Ecol Sociobiol

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Animals generally adjust their behavior in response to bodily state (e.g., size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against the risk of starvation. Here, we investigated whether brown trout Salmo trutta adjust their behavior in relation to energetic status and body size during a major early-life selection bottleneck, when fast growth is important. Over two consecutive time periods (P1 and P2; 12 and 23 days, respectively), food availability was manipulated, using four different combinations of high (H) and low (L) rations (i.e., HH, HL, LH, and LL; first and second letter denoting ration during P1 and P2, respectively). Social effects were excluded through individual isolation. Following the treatment periods, fish in the HL treatment were on average 15–21 % more active than the other groups in a forced open-field test, but large within-treatment variation provided only weak statistical support for this effect. Furthermore, fish on L-ration during P2 tended to be more actively aggressive towards their mirror image than fish on H-ration. Body size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits, we could also distinguish two behavioral clusters: one consisting of more active and aggressive individuals and the other consisting of less active and aggressive individuals. This indicates that brown trout fry adopt distinct behavioral strategies early in life.Significance statementThis paper provides information on the state-dependence of behavior in animals, in particular young brown trout. On the one hand, our data suggest a weak energetic state feedback where activity and aggression is increased as a response to short term food restriction. This suggests a limited scope for behavioral alterations in the face of starvation. On the other hand, body size is linked to higher activity and aggression, likely as a positive feedback between size and dominance.The experiment was carried out during the main population survival bottleneck, and the results indicate that growth is important during this stage, as 1) behavioral compensation to increase growth is limited, and 2) growth likely increases the competitive ability. However, our data also suggests that the population separates into two clusters, based on combined scores of activity and aggression (which are positively linked within individuals). Thus, apart from an active and aggressive strategy, there seems to be another more passive behavioral strategy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00265-016-2215-y) contains supplementary material, which is available to authorized users.

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Section: Introductionsupporting

confidence: 55%

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Näslund

Johnsson

2016

Behav Ecol Sociobiol

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“…Our experimental design does not allow us to discern whether the absence of a relationship between fin and muscle telomere length is due to low stability of individual differences or tissue-specific processes. Yet, previous work on similar-aged brown trout suggests repeatable inter-individual differences in telomere length from two pectoral fins sampled one year apart (Rho = 0.463, p<0.0001, N=93, unpublished results from [51]). …”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Telomere length covaries with personality in wild brown trout

Adriaenssens

Pauliny

Blomqvist

et al. 2016

Physiology & Behavior

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The prevalence of consistent among-individual differences in behaviour, or personality, makes adaptive sense if individuals differ in stable state variables that shift the balance between the costs and benefits of their behavioural decisions. These differences may give rise to both individual differences in, and covariance amongst, behaviours that influence an individual's exposure to risks. We here study the link between behaviour and a candidate state variable previously overlooked in the study of state-dependent personality variation:telomere length. Telomeres are the protective endcaps of chromosomes and their erosion with age is thought to play a crucial role in regulating organismal senescence and intrinsic lifespan. Following evidence that shorter telomeres may reduce the lifespan of animals in a wide range of taxa, we predict individuals with shorter telomeres to behave more boldly and aggressively. In order to test this, we measured telomere length and behaviour in wild juvenile brown trout (Salmo trutta). We found individuals with shorter fin telomeres to behave consistently more boldly and aggressively under controlled conditions in the laboratory. No such relationship was found with muscle telomere length 3-4 months after the behavioural assays. We suggest that telomere dynamics are an important factor integrating personality traits with other state variables thought to be important in the regulation of behaviour, such as metabolism, disease resistance and growth.

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“…; Näslund et al. ). However, the compensatory response often declines in autumn, and in winter the growth rate converges with that of individuals not being food‐restricted, regardless of whether they have caught up in size or not (Johnsson & Bohlin ; Näslund et al.…”

Section: Introductionmentioning

confidence: 97%

Autumn food restriction reduces smoltification rate, but not over‐winter survival, in juvenile brown trout Salmo trutta

Näslund

Sundström

Johnsson

2015

Ecology of Freshwater Fish

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The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group.Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.

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Telomere dynamics in wild brown trout: effects of compensatory growth and early growth investment

Cited by 42 publications

References 47 publications

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry

Telomere length covaries with personality in wild brown trout

Autumn food restriction reduces smoltification rate, but not over‐winter survival, in juvenile brown trout Salmo trutta

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