In nature, organisms evolve to best fit their ecological niches, and while doing so, arrange themselves into discrete, reproductively isolated groups called species. While the evolutionary response of an organism is shaped by adaptive mutations, random genetic drift, and bottlenecks, the fundamental forces driving speciation events are largely unknown. In fact, speciation is, at times, characterized to be simply a by-product of an adaptive process. However, the reasons why an adaptive process defined by interaction between a genome and an environment, should dictate a process which is defined by interaction of two distinct genomes are not clear. While a number of theoretical and conceptual ideas and models have been proposed to explain speciation, no model systems or systematic experimental characterization of speciation events exists. This lack of understanding of speciation events forms the basis of our work. In this context, a study of factors that contribute to the process of speciation is of interest to us. Towards this end, we use Saccharomyces cerevisiae and the melibiose utilization system as the model system to study dynamics of speciation in allopatry and sympatry.