Theoretical and experimental evolution on genomes and mating systems

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My research focuses on evolutionary forces shaping the many features of an organism, including its life history, reproductive system, and genomic structure. Through mathematical modelling, experimental evolution, and statistical inference, our work helps explain the remarkable diversity among species and provides an improved basis for predicting evolutionary responses to changing environments. Here I outline research that my group will accomplish with NSERC funding.***Goal I: Advancing Evolutionary Theory*** My group will pursue a diverse array of mathematical models. As an example, I highlight research on conflicting selection pressures between haploid and diploid phases of sexual life cycles (“ploidally antagonistic selection”).*** We are investigating how evolution is predicted to shape the “selective arena” within which haploid pollen or sperm compete for fertilization in the face of such conflicts. This theoretical work fills an important gap by predicting when haploid selection is likely to be a major evolutionary force.*** We will also investigate how ploidally antagonistic selection impacts sex chromosome evolution. This theory promises to make novel predictions about the signatures of selection expected in sex-linked regions of the genome.******Goal II: Experimental Evolution in Yeast***My lab will use yeast to investigate the first steps towards speciation, studying reproductive incompatibilities that arise following exposure to a novel environment. Our preliminary results have revealed reproductive incompatibilities in about half of the crosses among resistance mutations that arose in the presence of the fungicide, nystatin. *** We propose three experiments to investigate this surprising finding:***(a) Evolve lines under continued exposure to nystatin to determine whether the initially strong incompatibility is maintained.***(b) Evolve lines to additional environmental challenges to test whether each bout of adaptation contributes further to isolation.***(c) Evolve lines to a slowly versus rapidly changing environment to test whether incompatibilities arise more commonly among large-scale than small-scale mutations. ***These experiments promise to shed light on when adaptation is most likely to generate new species. ******Goal III: Comparative Analyses***My research group also investigates long-term evolutionary processes across phylogenetic trees. *** An open methodological question is how to correct for biases in what researchers choose to study. Small or invariant groups of organisms are often ignored. Current methods do not account for such “acquisition biases”. We will develop statistical methods that correct for these biases.*** Empirically, we are performing large-scale analyses of the impact of sexual system on diversification. We are analyzing the distribution of dioecy (separate sexes) across the tree of life to test hypotheses for why dioecy is common in some groups but rare in others.**