An integrated molecular and ecological trait dataset for the Tuscan Archipelago butterflies: a resource to understand the evolution and extinction of island biodiversity

Island biogeography postulates the importance of integrating the study of molecular data with species traits in explaining the evolution of endemic taxa, the persistence of relicts and the extinction of populations, but so far very few empirical tests have used species‐rich animal groups over entire archipelagos. We assembled a dataset of DNA barcodes for the 52 butterfly species reported from the Tuscan Archipelago, including comparative material from neighbouring areas (Sardinia, Corsica and Tuscany). We also compiled data on 10 species traits and on the apparent disappearance of some of the butterfly species from the main islands of this archipelago in the last 115 years. We assessed: i) the phylogeographic structure of each species across the Ligurian‐Tyrrhenian area, as well as ii) the overall phylogeographic pattern in the same region, and iii) we identified the traits associated with population diversification, uniqueness, or recent extinction from specific islands. There was a considerable degree of population diversification in many species, which confirms that the Tuscan Archipelago hosts highly diverse butterfly communities. Phylogenetic regressions showed that smaller‐sized and more specialized species, with a preference for drier regions, display greater genetic structure and/or uniqueness. Moreover, species adapted to colder and wetter areas and with shorter flight periods are more likely to become extinct. The methodology used here can be applied to reveal fine‐scale diversity patterns, their origins and the vulnerability of taxa to current and future environmental changes, thus providing a valuable tool for evidence‐based conservation prioritization.