Abstract :
[en] Understanding why only some species succeed in naturalizing and invading ecosystems has intrigued scientists since Darwin's time. The pre-adaptation hypothesis posits that introduced species closely related to natives, therefore ecologically similar, are more likely to establish than others. This aligns with the climate matching hypothesis, by which mismatches between species' ecological requirements and local conditions act as barriers to establishment and naturalization. Conflicting evidence leaves the respective roles of biogeographic origin and climatic affinity in invasion risk prediction unresolved. Here, we examine how biogeographical origin, climatic matching, and phylogenetic relatedness influence the success of introduced plant species that are congeneric with native species in the Canary Islands, an oceanic archipelago with Mediterranean climatic affinities. We integrated phylogenetic, climatic and occurrence data at two levels: 1) interspecific comparisons of phylogenetic distances and climatic overlap between introduced species and their closest native counterpart; and 2) intraspecific analysis of realized climatic niches between native and invaded ranges. Most congeneric species originate from the Mediterranean Basin and temperate Europe and, to a lesser extent, the Neotropics. Phylogenetic distance did not significantly contribute to climatic overlap between native and introduced congeneric species, ruling out the pre-adaptation hypothesis and questioning the generality of phylogenetic niche conservatism in promoting invasion success. Intraspecific analyses showed that over one-third of species exhibited an expansion of their realized climatic niche towards climatic space not occupied in the native ranges. These results indicate that climatic niche expansion, potentially driven by ecological release from natural or anthropogenic biotic constraints, or by in situ evolution, may represent an important process in biological invasions. Our findings highlight the prevalence of niche expansion among introduced plant species in the Canarian archipelago and suggest a role in facilitating invasion within this archipelagic context, with potential implications for risk assessment in increasingly disturbed insular regions worldwide.
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