Tiemersma, R. (Ron) (2019) On Parasite-Mediated Diversification in Haplochromine Cichlids: Ectoparasite Infection Patterns are Different between Species in Natural Conditions but Similar in Controlled Environments. thesis, Medicine.
Full text available on request.Abstract
Determining the mechanisms by which hosts adapt to parasites and vice versa may enhance our understanding of biodiversity dynamics and of the epidemiology and etiology of infectious diseases. In this study, the role of parasites in diversification of their hosts is investigated in haplochromines from Lake Victoria. Haplochromines are a highly diverse tribe of cichlid fish which have undergone rapid divergence, making them an ideal model system to study evolutionary phenomena. Parasite-mediated selection leading to species-specific resistance has been proposed as a contributor to their diversification, as different species display different infection patterns in the wild. If species-specific resistance indeed occurs, parasite infection patterns should be maintained under similar parasite exposure. To assess this hypothesis, cichlids were bred in aquaria harbouring gill-infesting ectoparasites of three different taxa. Parasite prevalence and intensity were assessed in four cichlid species and hybrids between two of these species. No differences in infection patterns between host species in the aquaria were observed, suggesting that differences in the wild are predominantly caused by environmental factors. However, first generation hybrid species showed a higher infection prevalence and intensity compared to their second generation counterparts, suggesting quick adaptation. The development of parasite resistance might be under different selection pressure in these controlled environments than in the wild, enabling other trade-offs. We conclude that our results do not provide evidence for parasite-mediated selection initiating host divergence in the investigated haplochromine species. These findings might aid in generating novel insights in diversification and in the evolution of resistance against parasites.
| Item Type: | Thesis (UNSPECIFIED) |
|---|---|
| Supervisor name: | Gobbins, T.P. (Tiziana) and Maan, Prof. Dr. M.E. (Martine) |
| Faculty: | Medical Sciences |
| Date Deposited: | 17 Sep 2020 10:05 |
| Last Modified: | 17 Sep 2020 10:05 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/2764 |
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