Microbial communities exist in heterogeneous environments. Phenotypic plasticity occurs when individuals respond to this heterogeneity, resulting in a diversity phenotypes within one species. This phenotypic diversity plays a role in the community composition and community stability in the face of both short-term and long-term environmental fluctuation. In the yeast species, Saccharomyces cerevisiae, one trait that exhibits phenotypic plasticity is sporulation rate. It has been suggested that differences in sporulation rate act as an ecological trade-off that may promote coexistence between populations of yeast that would normally compete, and thereby maintains genetic diversity within the population. What role does a yeast strain’s global region of origin play in its plasticity and the presence of this ecological trade-off? We analyzed five wild strains of the yeast Saccharomyces cerevisiae from five different global regions attempting to understand the different mechanisms used to compete for resources, respond to environmental fluctuations and facilitate coexistence. Our analysis included quantification of survivorship of both life-history states of the yeasts—actively dividing vegetative cells or metabolically quiescent spores— when they were vectored through the gut of. Additionally, we analyzed the effectiveness of regionally-based, possible alternative survival strategies in certain regional strains of yeast within the S. cerevisiae species.
Results/Conclusions
We found that between sporulated and vegetative states of each strain, regardless of region, there was a higher rate of survival of the sporulated strains relative to its vegetative counterpart. This differential survival may indicate a trade-off with sporulation rate: cells that are quick to sporulate reduce their reproductive success, but survive to reproduce later; whereas cells that are slow to sporulate reproduce longer However, consideration of the survival by region proved to be much more informative. We found that strain regionality affected multiple outcomes including the ratio of survivorship between vegetative and sporulated cells, the rates of sporulation and vegetative growth pre- and post-digestion, and the levels of phenotypic plasticity exhibited overtime as the cells were repeatedly exposed to digestion treatments. The phenotypic characteristics of the European and Malaysian regions were notably different from the other three global regions, in both sporulation rate and response to digestion. These differences may function as alternative survival strategies when digested by insects or as an outcome of other region-specific selective pressures. Paired with differential insect preference data and post-digestive growth data, this data paints a more complete picture of microbe-insect community interactions based on the community’s global region.