Compatibility with killer explains the rise of RNAi-deficient fungi.

If you have ever wondered just how essential RNA interference (RNAi)-related processes are to eukaryotes, this analysis of how budding yeast has managed without these is essential reading. Although budding yeast (Saccharomyces cerevisiae) has for many years distinguished itself as one of the pre-eminent models for eukaryotic genetics, in more recent years it has also stood out as one of the few well-characterised eukaryotes that lack RNAi. The analysis by Dinnenberg et al. offers a balanced selection-based explanation for this deficiency, suggesting that it allows budding yeast to maintain an RNA virus that kills would-be competitors.