Temperature-Driven Changes In Behavioural Unpredictability And Personality In The Beadlet Sea Anemone, Actinia Equina

Unexplained behavioural inconsistency in individual animals, termed unpredictability, could account for more than 50% of variance in some behaviours. Unpredictability is likely to be selectively beneficial as a predator mitigation strategy and thus should be of adaptive value. Between-individual differences in behavioural unpredictability and how it changes across environmental contexts may thus have important consequences for selection, particularly in the face of extreme environmental changes. Associations between unpredictability and other risk-mitigating behavioural traits such as boldness could further influence individual fitness and population health. In this study, we investigated patterns of unpredictability in Actinia equina individuals at high and low temperature extremes. We investigated two boldness-related behaviours, immersion response (tentacle extension with submergence) and startle response (tentacle extension after a fright). We took bursts of six repeated measures of each behaviour, one at 6 degrees C and one at 21 degrees C in two crossed-over treatments, and two at 13 degrees C in a control treatment. Large sample sizes allowed us to use double-hierarchical linear mixed modelling to investigate between-individual variation in unpredictability and in the plasticity of unpredictability. Significant between-individual variation in unpredictability was present for both behaviours and was influenced by temperature. For the startle response, animals collected from less stochastic environments were more unpredictable at 21 degrees C than those from more stochastic environments. For the immersion response, animals were more unpredictable at 21 degrees C than at 6 degrees C; this difference was clearer in those individuals that started at the high, rather than the low, temperature. Unpredictability was further positively correlated with the mean level immersion response at both temperatures; intermediate and moderately shy individuals were more unpredictable than bold in both environments. Metabolic rate in A. equina increases as the temperature rises, so energetically taxing unpredictability, coupled with reductions in foraging associated with shyer behaviour, could prove selectively detrimental during heatwaves. (C) 2021 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.