Reduced exploration capacity despite brain volume increase in warm-acclimated common minnow

Zavorka, L., Koeck, B. , Armstrong, T. A., Soganci, M., Crespel, A. and Killen, S. (2020) Reduced exploration capacity despite brain volume increase in warm-acclimated common minnow. Journal of Experimental Biology, 23, jeb223453. (doi: 10.1242/jeb.223453) (PMID:32414873) (PMCID:PMC7286289)

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While evidence suggests that warming may impact cognition of ectotherms, the underlying mechanisms remain poorly understood. A possible but rarely considered mechanism is that the metabolic response of ectotherms to warming is associated with changes in brain morphology and function. Here, we compared aerobic metabolism, brain volume, boldness and accuracy of maze solving of common minnows (Phoxinus phoxinus) acclimated for 8 months to either their current optimal natural (14°C) or warm (20°C) water temperature. Metabolic rates indicated increased energy expenditure in warm-acclimated fish, but also at least partial thermal compensation as warm-acclimated fish maintained high aerobic scope. Warm-acclimated fish had larger brains than cool-acclimated fish. The volume of the dorsal medulla relative to the overall brain size was larger in warm- than in cool-acclimated fish, but the proportion of other brain regions did not differ between the temperature treatments. Warm-acclimated fish did not differ in boldness but made more errors than cool-acclimated fish in exploring the maze across four trials. Inter-individual differences in the number of exploration errors were repeatable across the four trials of the maze test. Our findings suggest that in warm environments, maintaining a high aerobic scope, which is important for the performance of physically demanding tasks, can come at the cost of changes in brain morphology and impairment of the capacity to explore novel environments. This trade-off could have strong fitness implications for wild ectotherms.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Killen, Professor Shaun and Crespel, Dr Amelie and Koeck, Dr Barbara and Zavorka, Dr Libor and Soganci, Mr Mustafa and Armstrong, Miss Tiffany
Authors: Zavorka, L., Koeck, B., Armstrong, T. A., Soganci, M., Crespel, A., and Killen, S.
College/School:College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Journal of Experimental Biology
Publisher:Company of Biologists
ISSN (Online):1477-9145
Copyright Holders:Copyright © 2020 The Company of Biologists Ltd
First Published:First published in Journal of Experimental Biology 223: jeb223453
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
167015The Influence of Individual Physiology on Group Behaviour in Fish SchoolsShaun KillenNatural Environment Research Council (NERC)NE/J019100/1Institute of Biodiversity, Animal Health and Comparative Medicine