Are preferences for yeasts stable or contextual?

Whether there are general mechanisms, driving interspecific chemical communication is uncertain. yeast and fruit flies, both extensively studied research models, share the same fruit habitat, and it has been suggested their interaction comprises a facultative mutualism that is instigated and maintained by yeast volatiles. Using choice tests, experimental evolution, and volatile analyses, we investigate the maintenance of this relationship and reveal little consistency between behavioral responses of two isolates of sympatric species. While was attracted to a range of different yeasts and this was independent of fruit type, preference appeared specific to a particular genotype isolated from a vineyard fly population. This response, however, was not consistent across fruit types and is therefore context-dependent. In addition, attraction to an individual isolate was pliable over ecological timescales. Volatile candidates were analyzed to identify a common signal for yeast attraction, and while generally responded to fermentation profiles, preference was more discerning and likely threshold-dependent. Overall, there is no strong evidence to support the idea of bespoke interactions with specific yeasts for either of these genotypes. Rather the data support the idea are generally adapted to sense and locate fruits infested by a range of fungal microbes and/or that yeast- interactions may evolve rapidly.