Was thinking about natural "zero calorie" sweetness and how these compounds could come to be via evolution. I was specifically thinking about monk fruit. While artificial selection likely played a role in the life history of the modern cultivated variety, this plant still needed to initially possess sweetness traits for humans to select. It seems to me to be an interesting case of mimicry--copy the palatability signal of caloric value of other fruits while not devoting valuable resources to creating equivalent amounts of sugars--because it depends on those other fruits/foods being consumed often enough to sustain the propagating organism. This makes it hard to classify the nature to the relationship in the propagator-mimick-mimicked triangle: the propagator-mimick relationship may be read as parasitic, commensal or mutualistic depending how we consider the value of non-caloric nutritional factors for (reproductive) success. Same can be said for the mimick-mimicked relationship, as both benefit from the strengthening of the sweetness signal, but the true signal might infact benefit more under complete knowledge on the part of the propagator. As a strategy, it is also very interesting because it requires a generalist propagator in an ecosystem with a certain amount of biodiversity, so it seems more likely for this relationship to emerge in nutrient rich environments than poorer ones.
Can anyone think of other examples and are there any existing examinations of similar relationships in the literature?