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Experimental manipulation of perceived predation risk and cortisol generates contrasting trait trajectories in plastic crucian carp

Author:
  • Jerker Vinterstare
  • Kaj Hulthén
  • P. Anders Nilsson
  • Helen Nilsson Sköld
  • Christer Brönmark
Publishing year: 2020-02-18
Language: English
Publication/Series: The Journal of experimental biology
Volume: 223
Document type: Journal article
Publisher: The Company of Biologists Ltd

Abstract english

Most animals constitute potential prey and must respond appropriately to predator-mediated stress in order to survive. Numerous prey also adaptively tailor their response to the prevailing level of risk and stress imposed by their natural enemies, i.e. they adopt an inducible defence strategy. Predator exposure may activate the stress axis, and drive the expression of anti-predator traits that facilitate survival in a high-risk environment (the predation-stress hypothesis). Here, we quantified two key morphological anti-predator traits, body morphology and coloration, in crucian carp reared in the presence or absence of a predator (pike) in addition to experimental manipulation of physiological stress via implants containing either cortisol or a cortisol inhibitor. We found that predator-exposed fish expressed a deeper-bodied phenotype and darker body coloration as compared with non-exposed individuals. Skin analyses revealed that an increase in the amount of melanophores caused the dramatic colour change in predator-exposed fish. Increased melanization is costly, and the darker body coloration may act as an inducible defence against predation, via a conspicuous signal of the morphological defence or by crypsis towards dark environments and a nocturnal lifestyle. By contrast, the phenotype of individuals carrying cortisol implants did not mirror the phenotype of predator-exposed fish but instead exhibited opposite trajectories of trait change: a shallow-bodied morphology with a lighter body coloration as compared with sham-treated fish. The cortisol inhibitor did not influence the phenotype of fish i.e. neither body depth nor body coloration differed between this group and predator-exposed fish with a sham implant. However, our results illuminate a potential link between stress physiology and morphological defence expression.

Keywords

  • Behavioral Sciences Biology
  • Colour change
  • Inducible defences
  • Phenotypic plasticity
  • Stress
  • Stress axis

Other

Published
  • ISSN: 1477-9145
Christer Brönmark
E-mail: christer [dot] bronmark [at] biol [dot] lu [dot] se

Head of unit

Division aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Professor

Aquatic Ecology

50

Professor

Division aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Research group

Aquatic Ecology

Projects

Doctoral students and postdocs

PhD students, main supervisor

Jerker Vinterstare

PhD students, assistant supervisor

  • Nan Hu
  • Varpu Pärssinen
  • Yongcui Sha
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