Evidence for toxin-encoding coinfections driving intransitive dynamics between allelopathic phenotypes in natural yeast populations

The available datasets include natural yeast isolate survey data collected across three years, including microsatellite information and metadata, as well as data from a follow-up time-shift experiment designed to test whether the distributions of wild yeast isolates are influenced by whether or not they have resistance to the toxins produced by killer yeast in the population.

Methods
Wild Saccharomyces cerevisiae isolates were collected from vineyards across New Zealand in 2018, 2019, and 2021. Colonies from wine ferments were picked and genotyped using microsatellite markers. Each isolate was then screened for dsRNA infections, focusing on totiviruses and toxin-encoding satellites. We first analyzed whether specific genotypes were associated with these toxin-encoding coinfections. Upon identifying a genotype that exhibited a significant decline across its entire range from one year to the next, we conducted time-shift killer assays. These assays tested whether competitors of the killer genotype in sympatric sites were resistant to the toxin, whether competitors in allopatric sites were susceptible, and whether isolates from sympatric sites, after the killer genotype had disappeared, were also sensitive, suggestive of a re-emergence of toxin sensitivity in the absence of the killer genotype.