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Unformatted text preview: ORIGINAL ARTICLE Birdflower interactions in the Macaronesian islands Alfredo Valido*, Yoko L. Dupont and Jens M. Olesen Department of Ecology and Genetics, University of Aarhus, Aarhus C, Denmark *Correspondence: Alfredo Valido, Estacio n Biolo gica de Don ana (CSIC), Avda. M a Luisa s/n, Pabello n del Peru , E-41013 Sevilla, Spain. E-mail: [email protected] ABSTRACT Aims Several bird-pollinated or ornithophilous flowers are present on the Macaronesian archipelagos, the Canary Islands and Madeira, but absent from nearby NW Africa and Europe. In Macaronesia, no spet nectar-feeding birds are found, but several generalist passerine bird species visit flowers for nectar. Two hypotheses attempt to explain the origin and evolution of ornithophily in the Macaronesian flora. According to the island de novo hypothesis, bird-flowers evolved from mainland insect-pollinated ancestors after island colonization. Alternatively, ancestors of the ornithophilous Macaronesian plant species evolved bird-flowers before reaching the islands (the relict hypothesis). In this study we first compile information of Macaronesian birdflower interactions from the literature and our own field observations. Secondly, we discuss the two hypotheses of origin of ornithophily in the light of evidence from recent molecular plant phylogenies, palaeontology, historical biogeography of the African avifauna and flora, and present-day ecological patterns. Location Madeira and Canary Islands. Results At least eleven endemic Macaronesian plant species from six genera have typical ornithophilous floral traits. These genera are: Canarina and Musschia (Campanulaceae), Isoplexis (Scrophulariaceae), Echium (Boraginaceae), Lotus (Fabaceae) and Lavatera (Malvaceae). These lineages have clear affinities to the Mediterranean region, except for Canarina whose closest relatives grow in East African mountains. Six generalist passerine bird species of Sylvia , Phylloscopus (Sylviidae), Serinus (Fringillidae) and Parus (Paridae) visit this flora for nectar. Main conclusion We suggest that the origin and evolution of ornithophilous traits in these plant species took place mostly in mainland areas prior to island colonization. In Canarina and Lavatera , it is well supported that ornithophily is a relict condition, which originated in mainland areas possibly in association with spet nectar-feeding birds. For the remaining plant species except Echium wildpretii bird floral traits probably also are a relict condition. These species may be derived from ancestors, which were visited by spet nectar-feeding birds during geological periods when the Mediterranean and the Ethiopian vegetation were intermingled in mainland Africa. Probably, these mainland ancestors went extinct due to severe climatic fluctuations, while their Macaronesian descendants survived in refuge on the islands. Finally, the island de novo hypothesis may explain the evolution of a mixed bird/insect-pollination system in the neo-...
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This note was uploaded on 07/17/2008 for the course EEOB 700 taught by Professor Wolfe during the Winter '05 term at Ohio State.
- Winter '05