Micromeria

 
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Micromeria in the Canary Islands


The genus Micromeria is composed of approximately 50 species of perennial herbs and shrubs whose centers of diversity are in the Mediterranean region and the Canary Islands (Bräuchler et al. 2005). On the Canary Islands and Madeira, this genus includes 16 species and 13 subspecies (Pérez de Paz 1978), some of which are restricted endemics and some occur on more than one island. One species, Micromeria varia Benth., is wide spread and can be found on the whole archipelago and Madeira. Molecular analysis using several DNA markers showed that all species on a single island appear to be monophyletic regardless of the species concept (Meimberg et al. 2006a).


Micromeria in Tenerife Island


In the island of Tenerife, the different age of its geological parts resulted in relict species with narrow palaeo-endemic ranges and a recent, ongoing radiation. This radiation is assumed to be initiated from these older species: M. densiflora Benth. on the Teno massif (16 million years old), M. rivas-martinezii Wildpret and M. glomerata Perez de Paz on Anaga (10 million years old).


Micromeria teneriffae Benth. occurs with two varieties on the south coast of the Anaga massif and adjunct areas of the southern coast, and M. varia occurs from the Teno to the Anaga massifs. The central part of Tenerife that has been formed by the Teide volcano about 200 000 years ago is habitat of three closely related species that are assumed to have descended from M. varia: M. lasiophylla Webb & Berthel. and M. lachnophylla Webb & Berthel. both high altitude endemics and M. hyssopifolia Webb & Berthel. that occurs from 0-2000 m above sea level in three varieties. Remarkably this species can be found in the northern slopes of Tenerife with very high precipitation as well as in coastal areas in arid conditions. This pattern of species distribution makes Micromeria on Tenerife a very good model to test the role of gene flow at contact zones for adaptive evolution. Not only remnants of the potential source species can be found on Tenerife but also multiple young derivates that are ecologically differentiated and can be used for comparative analysis.

























Micromeria in Gran Canaria Island


In the island of Gran Canaria, the second biggest island of the Canary Archipelago, there are 3 narrow endemics: M. pineolens Svent. restricted to the NW of the islands between 700-1400m. Micromeria leucantha Svent. ex P. Pérez is restricted to the Viso mountain and the cliffs of Pino Gordo and Guy-Guy while M. helianthmifolia Webb & Berthel. inhabits the Caldera de Tirajana, to the S of the island. Micromeria lanata Benth. and M. benthamii Webb & Berthel. are two sympatric and abundant species in the central part of the island above 700 m. Micromeria linkii Webb & Berthel. is common along the N coast of the island and M. tenuis (Link) Webb & Berthel. inhabits the W part of the island between 200-800 m. Micromeria varia is widely distributed around the whole island with two subspecies: subsp. canariensis P. Pérez to the N of Gran Canaria and subsp. meridialis P. Pérez to the S.


Micromeria in the other islands of the Canary Archipelago


Compared to the biggest islands of the archipelago, the remaining islands are relatively poor in number of species of Micromeria. La Palma presents M. herpyllomorpha Webb & Berthel., M. lasiophylla, and M. varia subsp. varia. El Hierro has only two species: M. hyssopifolia and M. varia subsp. hierrensis P. Pérez. while Gomera presents M. lepida Webb & Berthel, and two subspecies of M. varia: subsp. varia and subsp. gomerensis P. Pérez. Lanzarote and Fuerteventura have only M. varia subsp. rupestris (Webb & Bertherl.) P. Pérez.