Harnessing the power of digital droplet PCR to conduct real-world microbial competitions

The budding yeast, Saccharomyces cerevisiae, has a long and storied history as a model organism for genetic, cellular and molecular biological research. More recently, researchers have sought to understand the ecology and evolution of its sister species, Saccharomyces paradoxus, in part to put our vast knowledge of the model yeast into its natural context (Replansky et al. ). However, the research tools have been limited, and most investigations into natural populations have either been descriptions of patterns of biogeography or taken the organism back into the laboratory for mating, growth and competition assays (Kuehne et al. ; Miller & Greig ; Murphy & Zeyl ; Samani et al. ). The link between what occurs out in the real world and what is measured in the laboratory has not yet been made, as so much is still unknown about the natural history of these yeasts. In this issue of Molecular Ecology Resources, Boynton et al. () take a major step towards bridging laboratory studies with field ecological research. By isolating a panel of S. paradoxus strains from a wooded area, culturing them in the laboratory, reintroducing pairs back into their habitat on natural substrate and monitoring the frequency of individual strains using digital droplet PCR, the researchers were able to use the framework of laboratory-based microbial competitions, but conduct them in a natural setting. While there is still more to learn about how to optimize this approach, it represents an exciting step in microbial ecological research and should prove an important tool for other species and numerous ecological questions.