Madison Reporter

In a study published in the journal Science, a team of researchers led by scientists at the University of Wisconsin–Madison and Vanderbilt University has made significant strides in understanding the evolution of yeasts, offering insights into why some species are generalists while others are specialists.

The study, based on one of the most comprehensive genomic datasets ever compiled, sheds light on a longstanding question in evolutionary biology. According to UW–Madison professor of genetics Chris Todd Hittinger and Vanderbilt professor of biology Antonis Rokas, the research team mapped the genetic blueprints, appetites, and environments of over 1,000 yeast species, revealing how these single-celled fungi have evolved over the past 400 million years.

Hittinger expressed surprise at the findings, stating, “Specialists should be better at the carbon sources for which they are specialized. And generalists, if they’re eating everything, they should not be as good. And instead, that’s not what we see.”

The research project, spanning a decade, aimed to build a comprehensive database linking genomes and traits of yeasts, a genetically diverse group comparable to all animals. This dataset is the most extensive ever compiled for such a diverse and ancient group.

The study focused on a group of yeasts distantly related to baker's yeast, examining their genomes and metabolisms. Hittinger's team utilized machine learning tools to understand the genes associated with various traits, including the organisms' ability to use different resources or tolerate different conditions, known as "niche breadth."

The findings challenge existing theories about evolutionary specialization, showing that internal factors, rather than external ones, primarily drive the differences in the types of carbon yeasts can consume. The data also revealed that generalists can utilize a wider range of carbon and nitrogen sources compared to specialists, without any apparent trade-offs.

Co-author Dana Opulente noted that the study found generalists and specialists in various environments, contrary to expectations. While the research has its limitations, the team believes that gathering more data from natural environments could provide further insights into niche breadth.

The study, supported by various grants, has opened up new avenues for research into biodiversity and the potential applications in industries such as biofuel production. Despite the progress made, unanswered questions remain, including why not all yeasts are generalists.

Hittinger concluded by pointing out the ongoing evolutionary process through which specialists may continually evolve from generalists. The team's work represents a significant contribution to understanding the complex dynamics of evolutionary biology.