The islands have been considered the best natural laboratories for the study of plant and animal evolution. They are unique and highly simplified worlds, home to a rich biota that includes a high percentage of endemic species. Their evolutionary uniqueness and isolation make island inhabitants prone to extinction in a scenario of climate change and biodiversity crisis. Island taxa form simplified communities, in which ecological relationships and evolutionary processes can be studied more easily than on the mainland. The Balearic Islands, like all islands in general, are especially vulnerable to global change and human disturbance. Due to its small territory, its rich biodiversity (including some 555 endemic animal and 130 plant taxa) is threatened by habitat loss and the introduction of allied species. A line of research focused on biodiversity and conservation issues is currently highly demanded by the Balearic society, one of the most aware in Spain in this regard. The team that meets at IMEDEA under this line of research has extensive experience in taxonomic, biogeographical, evolutionary and ecological issues of island biotas. The methodological approach is multidisciplinary, combining morphological, distributional, population and various types of molecular data to improve our understanding and promote the conservation of unique island biotas.