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Evolution of phenotypic variation

Abstract:

The knowledge about how phenotypic variation evolves can help us to reveal the way populations are shaped which determines whether an organism displaying certain phenotypic trait has the ability to respond to environmental changes. The main goal of this PhD thesis is to reconstruct the genetic changes underlying observed phenotypic variation during the course of evolution at different phylogenetic distances. In our work we considered both discrete and continuous phenotypic traits and approached their study by applying comparative methodologies at the genomic and/or transcriptomic levels. In the first part of the thesis we investigated the evolution of the plant pathogenic phenotype in Ascomycetes by comparing the genomes, as well as the transcriptomes of pathogenic and non-pathogenic species. This allowed us showing that most of the genes related to pathogenesis were already present in the ancestor of the Ascomycete lineages we used in our study. Species that did not develop the pathogenic phenotype seemed to have reduced their genetic complexity compared to their ancestors. At the transcriptomic level, plant pathogenesis is likely the result of various mechanisms including: expression divergence of direct orthologs between pathogens and non-pathogens, gene dosage and neofunctionalization of duplicated genes, and fast expression evolution of entire gene families. In the second part of the thesis we focusded on the evolution of phenotypic traits with a continuous variation and studied the tolerance to high ethanol phenotype in yeast. We developed a novel methodology called EXPLoRA for the analysis of data from Bulk …