Niche Breadth and Olfactory Context Shape Informed Passive Dispersal

Animals must decode environmental information to make adaptive decisions. In passive dispersers, for whom only departure timing is under control, the mechanisms of take-off remain poorly understood. Using experimental evolution, we tested how niche breadth modulates passive dispersal in phytophagous mites by exposing specialist and generalist lineages to host-derived kairomones. Dispersal was highly context-dependent. Generalists exhibited higher baseline dispersal and increased take-off when detecting familiar target cues; however, they were inhibited by complex mixtures of unfamiliar cues (low signal-to-noise ratio). Conversely, specialists primarily tracked current host quality, departing significantly more frequently from unfamiliar plants, yet showing little modulation by target cue identity. These results demonstrate that divergent host specialisation in homogeneous versus heterogeneous environments fundamentally alters the way in which organisms integrate information from current and future habitats to drive dispersal. Niche breadth dictates the baseline propensity for informed departure, while olfactory context provides the final trigger for passive take-off.