Body length rather than routine metabolic rate and body condition correlates with activity and risk‐taking in juvenile zebrafish Danio rerio

Abstract

In this study, the following hypotheses were explored using zebrafish Danio rerio: (1) individuals from the same cohort differ consistently in activity and risk-taking and (2) variation in activity and risk-taking is linked to individual differences in metabolic rate, body length and body condition. To examine these hypotheses, juvenile D. rerio were tested for routine metabolic rate and subsequently exposed to an open field test. Strong evidence was found for consistent among-individual differences in activity and risk-taking, which were overall negatively correlated with body length, i.e. larger D. rerio were found to be less active in a potentially dangerous open field and a similar trend was found with respect to a more direct measure of their risk-taking tendency. In contrast, routine metabolic rate and body condition were uncorrelated with both activity and risk-taking of juvenile D. rerio. These findings suggest that body length is associated with risk-related behaviours in juvenile D. rerio for which larger, rather than smaller, individuals may have a higher risk of predation, while the role for routine metabolic rate is relatively limited or non-existent, at least under the conditions of the present study.

Size‐selective harvesting fosters adaptations in mating behaviour and reproductive allocation, affecting sexual selection in fish

“…Given that the selection lines we studied evolved different terminal sizes (Figure ), the standardization of size across selection lines implies that we used fish from the extremes of the size distributions of the different selection lines (upper percentiles for the large‐harvested line and lower percentiles for the small‐harvested line). Size variation within a cohort correlates with personality in zebrafish (Polverino, Bierbach, Killen, Uusi‐Heikkila, & Arlinghaus, ). Therefore, we may have sampled different personalities from the selection lines, thereby possibly confounding our results.…”

A meta‐analysis of fish behavioural reaction to underwater human presence

“…Many alternative hypotheses have been highlighted to explain why larger fish flee at a greater distance than smaller fishes (Domenici, 2010). These hypotheses could be directly linked to the long-time evolutionary arms race between predators and prey, where morphological defences such as armour evolved in response to greater predation risk (Hodge et al, 2018), or they could be linked to energy requirements where smaller fish must act bolder to obtain food, or smaller fish pay a relatively higher opportunity cost for leaving-particularly if they are successfully foraging (Dill, 1990;Grand & Dill, 1997;Paglianti & Domenici, 2006;Polverino, Bierbach, Killen, Uusi-Heikkili, & Arlinghaus, 2016). At a shorter time scale, larger (and older) fish might also have developed greater escape reactions because they have been longer exposed to fishing pressures (Biro & Post, 2008;Johnston et al, 2013;Tsikliras & Note: Estimates are average coefficients of the model, their associated standard error (SE) and the importance of each factor in explaining species responses to human disturbance (the closer than 1, the most important the factor).…”

Diel movement of brown trout,Salmo trutta, is reduced in dense populations with high site fidelity

“…Accordingly, the metabolic hypothesis (i.e., see Brown & Braithwaite, ; Krause, Loader, McDermott, & Ruxton, ) predicts that changes in movement are related to physiological status (e.g., hunger level, size of energy reserves) rather than body size itself. For example, smaller individual zebrafish ( Danio rerio Hamilton, 1822) were more active in areas with a potentially higher predation risk (Polverino, Bierbach, Killen, Uusi‐Heikkilä, & Arlinghaus, ). Similarly, smaller catfish ( S. glanis ) showed more motivation to search for shelter than larger conspecifics (Slavík et al., ).…”