The effect of different yeast variants of the yeast Saccharomyces cerevisiae on the outcome of competition between Drosophila simulans and D. melanogaster was investigated. In all experiments differential birth rate was the effective mode of species competition. Addition of live yeast and especially mixtures of yeast strains improved the competition situation of a species, but could not prevent the extinction.
Bos, M., Boerema, A., & Lammers, G. (1983). The effects of sterol mutants of the yeast Saccharomyces cerevisiae on the outcome of competition between Drosophila melanogaster and D. simulans. Genetica, 61(2), 89-97. https://doi.org/10.1007/BF00123218