This thesis comprises elementary work on the evolution of ageing. The issue of ageing, and especially of starvation resistance, has been approached from both the environmental and the genetic sides... Show moreThis thesis comprises elementary work on the evolution of ageing. The issue of ageing, and especially of starvation resistance, has been approached from both the environmental and the genetic sides that are of relevance to the issue. Therewith, this study has a broad orientation, varying from ecophysiology to selection experiments, mutant analysis and sate of the art microarray gene expression analysis. All this work was performed on Drosophila melnogaster, the fruit fly, and was put in an integrative context with human ageing. Show less
The several hundred species of cichlid fish endemic to Lake Victoria (East-Africa) are textbook examples of explosive speciation. This thesis evaluates the hypothesis that sexual selection by... Show moreThe several hundred species of cichlid fish endemic to Lake Victoria (East-Africa) are textbook examples of explosive speciation. This thesis evaluates the hypothesis that sexual selection by female mate choice has contributed to this process of divergence, by investigating the mechanisms that drive the evolution and divergence of mating preferences for colour patterns. I studied two representative model systems, the highly polymorphic species Neochromis omnicaeruleus and the species pair Pundamilia nyererei and P. pundamilia. I used observational and experimental approaches in both laboratory and field. My work indicates that the interaction between sexual selection and habitat heterogeneity, in terms of photic environment and parasite exposure, can promote population divergence in male nuptial coloration and female preferences. In contrast, predation pressure and water turbidity may constrain the evolution and persistence of conspicuously coloured morphs and species. Show less
The aim of the studies described in this thesis was to investigate the genome organization of rodent malaria parasites (RMPs) and compare the organization and gene content of the genomes of RMPs... Show moreThe aim of the studies described in this thesis was to investigate the genome organization of rodent malaria parasites (RMPs) and compare the organization and gene content of the genomes of RMPs and the human malaria parasite P. falciparum. The release of the complete genome sequence of P. falciparum and partial genome sequences of three RMPs (Plasmodium yoelii - Chapter 3; Plasmodium berghei and Plasmodium chabaudi - Chapter 4) enabled us to expand the analysis to a genome-wide survey. By aligning the RMP contigs against the P. falciparum genome, a composite RMP genome was constructed, which was subsequently compared in detail with the P. falciparum genome (Chapter 5). These comparative analyses showed high levels of conservation in both genome organization and gene content (~85%), supporting the use of RMPs as models for human malaria infection. P. falciparum-specific genes located in both subtelomeric and core regions of the chromosomes were also found and included many genes involved in host-parasite interactions, such as host cell invasion and evasion of the human immune response. Finally, reverse genetics approaches were used to study the function of certain genes that are conserved between the rodent and human malaria parasites (Chapters 6 & 7). Show less
