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Title: Long live the Red Queen? : examining environmental influences on host-parasite interactions in Daphnia
Author: Killick, Stuart C.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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The Red Queen hypothesis proposes that antagonistic coevolution between parasites and their hosts is responsible for the evolutionary maintenance of sexual reproduction. In this thesis I examine various aspects of the Red Queen hypothesis using the Cladoceran crustacean Daphnia. A survey of parasite prevalence in North American populations of Daphnia pulex represents the first attempt to examine the role of parasites in the maintenance of breeding system variation in this species. Despite evidence of over- and underparasitism in some populations, parasite prevalences were generally very low suggesting that parasites are not a major source of selection in the populations studied. The Pluralist Approach to sex proposes that the effects of deleterious mutations and parasitism may interact. I established mutant lines of Daphnia magna using the chemical mutagen ENU and investigated the impact of the parasite Pasteuria ramosa on mutation load under different environmental conditions. I found that although parasite infection could exacerbate the effects of mutation load, this interaction was dependent on host environment and the implications of these findings for the general application of the Pluralist Approach are discussed. The impact of mixed strain infections on genotype-specific infection was also examined. In natural populations, hosts are likely to be exposed to a range of parasite genotypes and this may potentially affect the efficiency of the immune response. I found that the ability of certain P. ramosa strains to infect their hosts is affected by prior host exposure to different strains.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available