Evolutionary winners are ecological losers among oceanic island plants

Aim Adaptive radiation, in which successful lineages proliferate by exploiting untapped niche space, provides a popular but potentially misleading characterization of evolution on oceanic islands. Here we analyse the respective roles of members of in situ diversified vs. non-diversified lineages in shaping the main ecosystems of an archipelago to explore the relationship between evolutionary and ecological ‘success’. Location Canary Islands. Taxon Vascular plants. Methods We quantified the abundance/rarity of the native flora according to the geographical range (number of islands where present and geographical extent of the range), habitat breadth (climatic niche) and local abundance (cover) using species distribution data based on 500 × 500 m grid cells and 2000 vegetation inventories located all over the archipelago. Results Species of diversified lineages have significantly smaller geographic ranges, narrower climatic niches and lower local abundances than those of non-diversified lineages. Species rarity increased with the degree of diversification. The diversified Canarian flora is mainly comprised by shrubs. At both archipelagic and island level, the four core ecosystems (Euphorbia scrub, thermophilous woodlands, laurel forest and pine forest) were dominated by non-diversified lineages species, with diversified lineages species providing <25% cover. Species of diversified lineages, although constituting 54% of the archipelagic native flora, were only abundant in two rare ecosystems: high mountain scrub and rock communities. Main conclusions Radiated species, endemic products of in situ speciation, are mostly rare in all three rarity axes and typically do not play an important role in structuring plant communities on the Canaries. The vegetation of the major ecosystem types is dominated by plants representing non-diversified lineages (species that derive from immigration and accumulation), while species of evolutionarily successful lineages are abundant only in marginal habitats and could, therefore, be considered ecological losers. Within this particular oceanic archipelago, and we posit within at least some others, evolutionary success in plants is accomplished predominantly at the margins.publishedVersio

Long-distance dispersal syndromes matter: diaspore-trait effect on shaping plant distribution across the Canary Islands

Oceanic islands emerge lifeless from the seafl oor and are separated from continents by long stretches of sea. Consequently, all their species had to overcome this stringent dispersal fi lter, making these islands ideal systems to study the biogeographic implications of long-distance dispersal (LDD). It has long been established that the capacity of plants to reach new islands is determined by specifi c traits of their diaspores, historically called dispersal syndromes. However, recent work has questioned to what extent such dispersal-related traits eff ectively infl uence plant distribution between islands. Here we evaluated whether plants bearing dispersal syndromes related to LDD – i.e. anemochorous (structures that favour wind dispersal), thalassochorous (sea dispersal), endozoochorous (internal animal dispersal) and epizoochorous (external animal dispersal) syndromes – occupy a greater number of islands than those with unspecialized diaspores by virtue of their increased dispersal ability. We focused on the native fl ora of the lowland xeric communities of the Canary Islands (531 species) and on the archipelago distribution of the species. We controlled for several key factors likely to aff ect the role of LDD syndromes in inter-island colonization, namely: island geodynamic history, colonization time and phylogenetic relationships among species. Our results clearly show that species bearing LDD syndromes have a wider distribution than species with unspecialized diaspores. In particular, species with endozoochorous, epizoochorous and thalassochorous diaspore traits have signifi cantly wider distributions across the Canary archipelago than species with unspecialized and anemochorous diaspores. All these fi ndings off er strong support for a greater importance of LDD syndromes on shaping inter-island plant distribution in the Canary Islands than in some other archipelagos, such as Gal á pagos and Azores.Peer reviewe