Abstract

The Saccharomyces cladeis a taxon of yeast, both wild and domesticated, which are capable of producing ethanol via fermentation, and have been utilised for this by humanity. This thesis uses whole-genome sequence data from over 200 novel isolates of two species – the predominantly domesticated Saccharomyces cerevisiae, and the partially domesticated Saccharomyces uvarum – from across New Zealand to investigate population structure and genomic signals of evolution after range expansion. Through a wide range of exploratory analyses, such as phylogenies, population structural analyses, and population genomics, the populations of these two species within New Zealand are characterized and their relation to their respective global populations evaluated. Genomic signatures of evolution are identified, and their possible adaptive value evaluated. Further areas of interest are highlighted, including strains of unusual ancestry and genes undergoing possible adaptive selection. Interspecies introgressions from the related Saccharomyces eubayanus are detected within the S. uvarum population in New Zealand, and the implications of such hybrid populations to species delimitation within the Saccharomyces are discussed in detail. The similarities and differences between the S. uvarum and S. cerevisiae populations are evaluated and related to the life histories of these species and the Saccharomyces as a whole to gain a deeper understanding of the genomic impacts of human-aided microbial dispersion.