Consequences Of Host Personality And Environmental Change For Parasite Infections In Freshwater Fish

The study of consequences of interaction between host personality and parasite infections can have significant ecological implications. To develop an understanding on the role of host personality on susceptibility of developing infection and disease progression following exposure to parasite infection a novel experimental study was conducted. The model host parasite system used in thesis was consisted of three-spined sticklebacks as host and Schistocephalus solidus as parasite. The results of this study show parasite infection can influence voluntary food intake as it progresses in host. In addition, personality type of host can affect the probability of developing infection. Whereas, no evidence of any significant interaction between host personality and parasite infections found on host-parasite biology. These results highlight that personality of animal can influence its fitness and parasite infection can have the potential to affect food intake by causing energetic drain. Furthermore, a novel experimental study demonstrated the significant effects of presence of conspecifics (social context) on personality. This result show that presence of conspecific can influence animal personality. The second part of the thesis investigated the importance of food availability and rising water temperature on aspects of the stickleback-Schistocephalus host-parasite relationship. While increasing temperature is known to influence parasite growth in this system, the potential interaction with food availability is unknown. The results of this novel study confirmed significant effects of increasing temperature on parasite growth with no additional effects of host food intake levels. Furthermore, the larger parasites establishing in fish held under the warmer temperature produced more eggs through in vitro culture techniques. In addition, elevated temperature also found to significantly influence level of neurotransmitters in the brains of sticklebacks. As animal are exposed to multiple stressors in wild, therefore the effects of multiple stressors i.e. pollutant (copper) and rising temperature on the parasite fitness were investigated. The results showed no significant effects of multiple stressors on parasite fitness. The final part of this thesis covers details of preliminary laboratory work conducted to develop Pimephales promelas-Ligula intestinalis as a model host-parasite system to investigate relevant question in the field of experimental parasitology and behavioural ecology. The overarching conclusion of the thesis is that environmental rise in temperature can potentially influence not only the host-parasite interaction/biology but underlying neurophysiological pathways controlling behaviour. Further study of interaction between personalities (consistent behaviour) and parasite infections with larger sample size can examine the subsequent effects of this interaction on host-parasite biology.