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Medientyp:
E-Artikel
Titel:
Different fates of island brooms: contrasting evolution in Adenocarpus, Genista, and Teline (Genisteae, Fabaceae) in the Canary Islands and Madeira
Beschreibung:
<jats:p>Analysis of sequence data from the internal transcribed spacers (ITS) and 5.8S region of nuclear ribosomal DNA show that Canarian and Madeiran brooms (Genisteae) of the genera <jats:italic>Teline</jats:italic>, <jats:italic>Adenocarpus</jats:italic>, and <jats:italic>Genista</jats:italic> are related to Mediterranean species and not to species from adjacent parts of Morocco. Each separate colonization of the islands has resulted in contrasting patterns of adaptation and radiation. The genus <jats:italic>Teline</jats:italic> is polyphyletic, with both groups (the “<jats:italic>T. monspessulana</jats:italic> group” and the “<jats:italic>T. linifolia</jats:italic> group”) separately nested within <jats:italic>Genista</jats:italic>. <jats:italic>Genista benehoavensis</jats:italic> (La Palma) and <jats:italic>G. tenera</jats:italic> (Madeira) form, with <jats:italic>G. tinctoria</jats:italic> of Europe, a single clade characterized by vestigially arillate seeds. The Canarian species of <jats:italic>Adenocarpus</jats:italic> have almost identical sequence to the Mediterranean <jats:italic>A. complicatus</jats:italic> and are likely to be the result of island speciation after a very recent colonization event. This Canarian/Mediterranean <jats:italic>A. complicatus</jats:italic> group is sister to the afrotropical montane <jats:italic>A. mannii</jats:italic> which is probably derived from an earlier colonization from the Mediterranean, possibly via the Red Sea hills. The independent colonization and subsequent radiation of the two <jats:italic>Teline</jats:italic> groups in the Canary Islands make an interesting comparison: the phylogenies both show geographical structuring, each with a central and western island division of taxa. Within the “<jats:italic>T. monspessulana</jats:italic> group” there is some evidence that both continental and Madeiran taxa could be derived from the Canary Islands, although it is likely that near contemporaneous speciation occurred via rapid colonization of the mainland and islands. The finding of two groups within <jats:italic>Teline</jats:italic> also has implications for patterns of hybridization in those parts of the world where <jats:italic>Teline</jats:italic> species are invasive; in California members of the <jats:italic>T. monspessulana</jats:italic> group hybridize readily, but no hybrids have been recorded with <jats:italic>T. linifolia</jats:italic> which has been introduced in the same areas.</jats:p>