TRUSTY, JENNIFER L.1*, ARNOLDO SANTOS-GUERRA2, TORTSTEN ERIKSSON1, and JAVIER FRANCISCO-ORTEGA1. 1Department of Biological Sciences, Florida International University, University Park, Miami FL, 33199 and Fairchild Tropical Garden, 11935 Old Cutler Road, Miami FL, 33156; 2Jardín de Aclimatación de La Orotava, Calle Retama Número 2, Puerto de La Cruz, Tenerife, Canary Islands E-38400, Spain; Bergianska Stiftelsen Kungliga Vetenskapsakademien, Box 50017, 104 05 Stockholm, Sweden. - Biodiversity, conservation and molecular phylogenies in the laurel forest of the Canary Islands: The case of a critically endangered taxon of Sambucus.
The laurel forests of the Canary Islands are a unique ecological zone
created by the cool and humid northeastern trade winds on the islandsí
northern slopes. These evergreen forests have several monotypic
endemic genera in addition to many endemic species which are
restricted to this ecological zone in the Canaries. It has been
suggested that most of the endemic plant species of the laurel forest
represent relictual elements of the flora which existed in the
Mediterranean basin during the Tertiary. These isolated taxa that have
not radiated into other ecological zones of the islands are considered
as typical examples of ancient Mediterranean stocks from the Tertiary.
Sambucus is an example of this kind of relictual taxa. This
genus has only one endemic species (S. nigra subsp.
palmensis) which is restricted to the laurel forests of the
islands of Tenerife, La Gomera, Gran Canaria, and La Palma. S.
nigra subsp. palmensis is considered as one of the most
rare of the laurel forest and special funds from the European Union
(Life Program) have been allocated for its conservation. A molecular
phylogeny of nucleotide sequences of the Internal Transcribed Spacers
of the nuclear ribosomal DNA of all the species of Sambucus
reveals: (1) S. nigra subsp. palmensis has a derived
position in the phylogeny which suggest that it colonized the laurel
forest recently and, (2) the ITS sequences of S. nigra, S.
nigra subsp. palmensis and S. nigra subsp.
maderensis are nearly identical. Our results concord with
previous morphological studies which suggested that S. nigra
subsp. palmensis can be considered subspecies of
Sambucus nigra. These results have conservation consequences,
mostly concerning priorities for conservation of the unique plant
biodiversity of the laurel forest of the Canary Islands.
Key words: Canary Islands, conservation, molecular phylogenies, Sambucus