DO YEASTS AND DROSOPHILA INTERACT JUST BY CHANCE?

<p>The fruit fly Drosophila melanogaster and the baker’s yeast Saccharomyces cerevisiae areclassic research model organisms that are also associated in nature, at least around vineyards.Sharing the same ephemeral fruit niche, winged Drosophila feed on immotile yeasts. That ayeast diet is essential for larvae development, and that saprophagous fruit flies are attracted toa suite of yeast volatiles, has been well established over the last century. Recently, researchhas focussed on the potential mutual benefit of this interaction hypothesising yeasts alsobenefit via dispersal from ephemeral fruits. It now appears that the concept of a co-evolvedmutualism between yeasts and Drosophila has permeated the literature. However, until robustevidence regarding the evolution and maintenance of this yeast-fly association has beenprovided, we suggest there is no compelling evidence to reject the more simplistic nullhypothesis that these interactions are due to exaptation, and not a mutualism driven by naturalselection.</p>