Ecological role of emergent properties in the chemodiversity landscape

Specialized metabolites released in the environment mediate ecological interactions across geographic scales and levels of biological organization. Whereas chemodiversity-the richness, relative abundance and disparity of specialized compounds within a blend of metabolites-has received substantial interest at the level of pairwise interactions, much less is known about how metabolites produced by multiple individuals and species merge into higher-level blends at population, community and ecosystem scales. Here we review evidence for emergent functions that arise from such higher-level chemodiversity: how blends can change in composition and functional consequence as they move through air, water and soil, and vary in time and space, thereby creating a dynamic chemodiversity landscape. We further discuss the applied potential of these chemodiversity landscapes and the threats that could compromise them. We outline key questions that will help to guide research on how higher-level chemodiversity contributes to ecological processes and functioning across scales.