Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour?

Abstract

Article (refereed) -postprintThomson, Jack S.; Watts, Phillip C.; Pottinger, Tom G.; Sneddon, Lynne U. 2012 Plasticity of boldness in rainbow trout, Oncorhynchus mykiss: do hunger and predation influence risk-taking behaviour? Hormones and Behavior, 61 (5). 750-757. 10.1016/j.yhbeh.2012.03.014 Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Boldness, a measure of an individual's propensity for taking risks, is an important determinant of fitness but is not necessarily a fixed trait. Dependent upon an individual's state, and given certain contexts or challenges, individuals may be able to alter their inclination to be bold or shy in response. Furthermore, the degree to which individuals can modulate their behaviour has been linked with physiological responses to stress. Here we attempted to determine whether bold and shy rainbow trout, Oncorhynchus mykiss, can exhibit behavioural plasticity in response to changes in state (nutritional availability) and context (predation threat). Individual trout were initially assessed for boldness using a standard novel object paradigm; subsequently, each day for one week fish experienced either predictable, unpredictable, or no simulated predator threat in combination with a high (2% body weight) or low (0.15%) food ration, before being reassessed for boldness. Bold trout were generally more plastic, altering levels of neophobia and activity relevant to the challenge, whereas shy trout were more fixed and remained shy. Increased predation risk generally resulted in an increase in the expression of three candidate genes linked to boldness, appetite regulation and physiological stress responses -ependymin, corticotrophin releasing factor and GABA A -but did not produce a significant increase in plasma cortisol. Plasticity of boldness in rainbow troutThe results suggest a divergence in the ability of bold and shy trout to alter their behavioural profiles in response to internal and exogenous factors, and have important implications for our understanding of the maintenance of different behavioural phenotypes in natural populations.

To boldly gulp: standard metabolic rate and boldness have context-dependent influences on risk-taking to breathe air in a catfish

“…T res was evaluated for evidence of a bimodal distribution, indicative of 'bold' versus 'shy' phenotypes (Frost et al, 2013;Huntingford et al, 2010;Thomson et al, 2012) because such typing into personalities (or 'coping styles') can be used to inform interpretation of individual variation in phenotypic traits in fishes (MacKenzie et al, 2009;Rey et al, 2013Rey et al, , 2015. The T res data were inspected visually for evidence of two groups, one with relatively short T res indicating bold individuals, and a second with relatively longer T res indicating shy individuals (Frost et al, 2013;Huntingford et al, 2010;Thomson et al, 2012).…”

“…The T res data were inspected visually for evidence of two groups, one with relatively short T res indicating bold individuals, and a second with relatively longer T res indicating shy individuals (Frost et al, 2013;Huntingford et al, 2010;Thomson et al, 2012).…”

“…Two groups, with mean (±s.e.) T res of 37±5 versus 181±14 min, were therefore designated as bold versus shy phenotypes, respectively (Frost et al, 2013;Huntingford et al, 2010;Rey et al, 2013;Thomson et al, 2012).…”

“…As variation in both sets of traits would contribute to a similar life-history trade-off, it has been predicted that correlational selection should co-adapt physiology and temperament: animals with higher basal oxygen demands should be bolder (Biro and Stamps, 2010;Careau and Garland, 2012;Jenjan et al, 2013;Réale et al, 2010;Stamps, 2007). There is evidence, however, that reality is more complex and that the relative strength of these drivers of risk-taking can vary with context, such as resource availability or perceived risks of predation (Frost et al, 2013;Killen et al, 2011Killen et al, , 2012Killen et al, , 2013Thomson et al, 2012).…”

The Integration of Sociality, Monoamines, and Stress Neuroendocrinology in Fish Models: Applications in the Neurosciences

“…behavioural and physiological differences prompted classifying animals into "proactive" and "reactive" coping styles, with the first describing individuals which are "bolder" (which can mean lower anxiety and/or increased impulsivity), more aggressive, dominant, and less flexible to fluctuations in the environment, and the second describing individuals which are "shyer", less aggressive, usually submissive, and more flexible to fluctuations (Øverli et al, 2007;Coppens et al, 2010). In outbred populations, however, there is consistent evidence (e.g., Frost et al, 2007Frost et al, , 2013; Thomson et al, 2012Thomson et al, , 2016) that bold rainbow trout are more flexible than shy fish. These discrepancies suggest that the reduced flexibility in bold individuals results from inbreeding and/or artificial selection, and is rare in the wild.…”