Many of the endemic species that are found on islands have very restricted distributions and naturally small population sizes, being therefore highly susceptible to extinction. Arthropods are among the animal groups most severely affected by extinction on islands, and although they represent more than half of the Azorean terrestrial endemic species, they were not used to assess conservation priorities in the Azores. In this study we used a multidisciplinary approach, including field surveys, traditional taxonomy, molecular assays, and the speciose beetle genera Tarphius and Trechus, to evaluate the adequacy of protected areas in the Azores in biodiversity preservation.
The data indicate that the area protected in the Azores is insufficient to guarantee the maintenance of species richness and genetic diversity of endemic Tarphius and Trechus beetles. Because all Tarphius and Trechus populations had exclusive haplotypes, and genetic variability within species is geographically structure, we argue that they should be treated as distinct conservation units and that the maximum number of populations should be protected in order to preserve current levels of biodiversity, and thus arrest the generalized trend of insular biodiversity decline.