Idiosyncratic hypothesis curve is:
The idiosyncratic hypothesis predicts no consistent, smooth relationship between species richness and ecosystem function. Effects depend on the particular identity, traits, and interactions of species lost or gained, so the response can rise, fall, or remain unchanged in an irregular and context-dependent way. A functional relationship should be interpreted by asking whether change is gradual, buffered, abrupt, or irregular. Gradual loss is consistent with accumulating contributions; an initial plateau suggests compensation; an abrupt drop points to loss of a disproportionately important speci
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 20