EARLY-LIFE DEVELOPMENT OF ANTIPREDATOR BEHAVIOUR OF JUVENILE NORTHERN CRAYFISH (FAXONIUS VIRILIS)

Predation is a major selective force shaping the behaviour and information use of prey species. In aquatic environments, prey frequently rely on chemical cues, such as conspecific alarm cues, to assess predation risk and guide antipredator responses. Early exposure to risk-related cues can influence the development of antipredator strategies, including generalized responses to novelty (neophobia) and the ability to learn predator recognition through associative conditioning. However, the extent to which embryos can use risk-related information to shape future antipredator behaviour remains less understood, particularly in aquatic invertebrates. In this thesis, I tested whether embryonic exposure to chemical risk cues influences the development of neophobia and learned predator recognition in juvenile northern crayfish (Faxonius virilis). In Experiment 1, gravid females carrying embryos were repeatedly exposed to either conspecific alarm cues (high-risk treatment) or water (low-risk treatment). Following hatching, juveniles were tested individually in behavioural trials designed to assess their generalized responses to novel stimuli. In Experiment 2, a similar protocol involved exposing gravid females to repeated pairings of an unknown cue with either alarm cues (true conditioning, known to mediate learned predator recognition), or water (pseudo conditioning). Juveniles were later tested for their ability to recognize the conditioned cue as risky. My results indicated that embryonic exposure to alarm cues did not induce generalized neophobia in juvenile crayfish. Additionally, pairing an unknown odour with alarm cues during embryonic development did not result in learned predator recognition in juveniles. These findings suggest that embryonic stages in crayfish may be limited in their capacity to form or retain cue-specific antipredator associations, potentially due to developmental constraints or insufficient reinforcement during early life. Together, these results highlight the importance of developmental timing and cue reliability in shaping antipredator behaviour in aquatic organisms.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Biology

Grantor

University of Saskatchewan

Year dc:date.issued

2026

Author dc:creator

• Fish, Katie

Committee members dc:contributor.committeemember

• Ferrari, Maud
• Chivers, Doug
• Phillips, Iain
• Gray, Jack
• Wei, Yangdou

• Predation
• learning
• neophobia
• predator-prey interactions

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/18810

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/18810