Molecular Ecology and Evolution
Puppo, Pamela , Curto, Manuel , Perez de Paz, Pedro Luis , Meimberg, Harald .
The role of secondary contact between previously isolated species: the genus Micromeria (Lamiaceae) on Tenerife.
Tenerife is the largest and highest island of the Canary Archipelago and has a complex geological history. Tenerife originated from three islands: Teno, Anaga, and Roque del Conde (4 to 12 myo) that got secondarily connected by a successive uprising of volcanoes forming its current outline 200 000 years ago. Interestingly, many of the older parts of the island contain distinct endemic species presumably remnants of an extinct flora.
Genus Micromeria (Lamiaceae) is represented by 17 species in the Canaries, of which eight occur on Tenerife. Three endemic species are restricted to the palaeo-island of Anaga and adjacent areas and one to Teno. In the geologically younger central part of the island five morphologically similar species grow with a wider distribution. It is quite likely that the younger parts of the island have been colonized from species coming from the old parts. As such, the central part of the island constitutes a secondary contact zone between the species and hybridization is regularly occurring between most of the species, as indicated by the presence of morphological hybrids.
We investigate the mechanisms that maintain the morphological differences between the species in the face of introgression. Post-zygotic barriers could impede gene flow despite hybridization. Alternatively, following the hybrid zone theory, parts of the genome could be stabilized by selection while neutral markers could be exchanged between the gene pools. Distinguishing between markers under purifying selection (length polymorphisms between alleles of coding genes) and presumably neutral microsatellite markers, we test for genetic differentiation between the species. The first results indicate little between-species differentiation and a surprisingly high genetic diversity of the restricted species. We hypothesize that introgressive hybridization homogenizes some parts of the genomes of these endemics, but that selection on genes important for local adaptation are responsible for maintaining the morphological differences.
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1 - University of Porto, Research Center in Biodiversity and Genetic Resources (CIBIO), Rua Padre Armando Quintas, Vairao, 4485-661, Portugal
2 - Universidad de La Laguna, Facultad de Farmacia, Av. Astrofisico Francisco Sanchez s/n, La Laguna, Tenerife, E-38200, Spain
Presentation Type: Oral Paper:Papers for Topics
Location: Westminster Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 3:00 PM