The Macaronesian species of Euphorbia sect. Aphyllis subsect. Macaronesicae are distributed in four of the five archipelagos of Macaronesia and two mainland enclaves in Portugal and Morocco. The aims of this study are to investigate the biogeographic history of
this group with AFLP and cpDNA markers, and to identify taxonomic entities within subsect. Macaronesicae based on genetic data, characterize them morphologically and infer the evolution of their diagnostic characters based on the reconstruction of ancestral character states. A continuous
spatial diffusion analysis of AFLP data implicated Tenerife (central Canary Islands) as the area of origin of the group, followed by colonization of other Canarian islands and other Macaronesian archipelagos. Two dispersal events back to the mainland were also inferred. Our phylogenetic network,
neighbour-joining clustering and Structure analyses of AFLP data demonstrated that species are genetically well delimited and suggested that they may have originated from a combination of allopatric speciation at broad scales (among islands) and fine scales (within islands), or possibly sympatric
ecological speciation followed by more recent inter-island dispersal events. Ancestral character state reconstructions of morphological characters suggested that the ancestor of subsect. Macaronesicae was adapted to arid or mesic habitats, and traits associated with adaptation to humid
habitats were acquired later. The central Canary Islands harbour the highest species diversity of this group in the Archipelago, and the highest nuclear and plastid genetic diversity. With regards to taxonomy, phylogenetic analyses and neighbour-joining clustering analyses based on AFLPs showed
two clearly differentiated genetic groups, sister to each other, which correspond to the E. atropurpurea and E. lamarckii complexes formerly recognised based on morphology. Euphorbia aphylla is recovered as sister to the rest of the species, supporting its exclusion from
the two complexes. Euphorbia tuckeyana is excluded from the E. lamarckii complex.
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ANCESTRAL CHARACTER STATE RECONSTRUCTION;
Document Type: Research Article
Institut Botànic de Barcelona (IBB – CSIC – ICUB), Pg. del Migdia s.n., 08038 Barcelona, Spain;, Email: [email protected]
Unitat de Botànica, Dept. Biologia Animal, Biologia Vegetal i Ecologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
The Morton Arboretum, 4100 Illinois Route 53, Lisle, 60532 Illinois, U.S.A.
Laboratori de Botànica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Avgda. Joan XXIII s.n., 08028 Barcelona, Spain
Institut Botànic de Barcelona (IBB – CSIC – ICUB), Pg. del Migdia s.n., 08038 Barcelona, Spain
Publication date: 2017-05-01
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