Investigations into the relationship between behavioural tendencies and social status using the signal crayfish Pacifastacus leniusculus as a model organism

Case, Jonathan Peter Nathaniel

Biological sciences
January 2013

Thesis or dissertation

© 2013 Jonathan Peter Nathaniel Case. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Many studies have shown that animals from a variety of taxa display behavioural tendencies which differ between individuals. If such tendencies are consistent over time and across contexts, they are generally referred to as personalities, temperaments or coping styles. Social conflict is believed to be one of the main factors leading to the evolution of animal personalities. Social conflict may favour the adoption of alternative behavioural options by individuals within a population, thus leading to differing personalities. In many animals, competition for resources leads to the establishment of social hierarchies, through agonistic encounters between conspecifics. Using the signal crayfish (Pacifastacus leniusculus) as a model organism this study investigated if crayfish of differing social status display different behavioural tendencies. To this end size-matched dominant and subordinate individuals were tested for boldness and activity at different time points. The behaviour was tested one day before, immediately after, one day after and six days after an agonistic encounter, in order to test whether crayfish display behavioural tendencies which are consistent over time and expressed in different behaviours and to determine whether pre-existing behavioural tendencies predispose individuals to a certain social status or only emerge as a result of status acquisition. The results show dominant and subordinate individuals differed significantly in their defensive behaviour. Subordinates also showed a high degree of consistency in their response to a predatory stimulus but dominants showed no consistency. In addition there was a negative correlation between the amount of low-offensive behaviour displayed during the agonistic encounter and the response to the predatory stimulus during the behavioural trials. Individuals which showed more low-offensive behaviour showed a weaker response to the predatory stimulus. Furthermore, individuals which showed more high offensive behaviour during the agonistic encounter had also spent more time walking on the day prior to the encounter.

Department of Biological Sciences, The University of Hull
Breithaupt, Thomas; Joyce, Domino A.
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