Small, isolated, and harbouring comparatively simple ecosystems, oceanic islands have been model systems of choice for biologists ever since Wallace and Darwin. However, any ecosystems that are spatially or temporally sharply delimited—e.g. temporal pools, deserts, alpine habitats, or ponds—can be considered to be islands. We study species interactions in insular systems, using oceanic islands as well as deserts and laboratory microcosms as model systems. We focus on: 1) the ecology of interspecies interactions, especially plant-animal interactions like pollination, seed dispersal, and herbivory; 2) understanding the consequences of environmental change and extinction for ecosystem functioning; 3) the conservation and restoration of plant-animal interactions, with a particular focus on how to resurrect lost interactions of recently extinct species by using replacement species.