Aim: Higher-elevation areas on islands and continental mountains tend to be separated by longer distances, predicting higher endemism at higher elevations; our study is the first to test the generality of the predicted pattern. We also compare it empirically with contrasting expectations from hypotheses invoking higher speciation with area, temperature and species richness. Location: 32 insular and 18 continental elevational gradients from around the world. Methods: We compiled entire floras with elevation-specific occurrence information, and calculated the proportion of native species that are endemic ('percent endemism') in 100 m bands, for each of the 50 elevational gradients. Using generalized linear models, we tested the relationships between percent endemism and elevation, isolation, temperature, area and species richness. Results: Percent endemism consistently increased monotonically with elevation, globally. This was independent of richness-elevation relationships, which had varying shapes but decreased with elevation at high elevations. The endemism-elevation relationships were consistent with isolationrelated predictions, but inconsistent with hypotheses related to area, richness and temperature. Main conclusions: Higher per-species speciation rates caused by increasing isolation with elevation are the most plausible and parsimonious explanation for the globally consistent pattern of higher endemism at higher elevations that we identify. We suggest that topography-driven isolation increases speciation rates in mountainous areas, across all elevations, and increasingly towards the equator. If so, it represents a mechanism that may contribute to generating latitudinal diversity gradients in a way that is consistent with both present-day and palaeontological evidence.

) in order to characterize the alien vascular plant flora of the island. The data analysed focus on different aspects of the alien flora such as diversity (species richness), abundance, lifeforms, vegetation belts, habitats and biogeographical origins. The results show that the alien species richness is currently high, representing 16.5% of the total flora, amongst which 37.5% are naturalized. The penetration of this flora occurs mainly at lower altitudes, and is still weak or absent in the higher altitude vegetation belts whereas it has increased over time within natural closed habitats. Over the last 11 years, the species richness of xenophytes has increased by 18.1%, which corresponds to an increase of 23.0% of the naturalized plants. Moreover, 24.8% of the alien taxa have increased in abundance. A scenario highlighting the trends of the introduced flora, and that includes issues of native biodiversity conservation, is proposed based on the results. The special case of invasive species is also considered, and their exponential increase on Corsica is highlighted. Other aspects of the alien flora, such as its taxonomic spectrum and biogeographical origins, are also analysed and are, whenever possible, compared with those of other geographical regions, particularly from the Mediterranean (Sardinia, Balearic Islands) and Continental Europe.

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