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Accueil du site → Doctorat → Autriche → DNA sequence and fingerprint (AFLP) analyses in the genus Hypochaeris (Asteraceae, Cichorieae) : inference of evolutionary patterns and processes from the specific to the populational level

Universität Wien (2004)

DNA sequence and fingerprint (AFLP) analyses in the genus Hypochaeris (Asteraceae, Cichorieae) : inference of evolutionary patterns and processes from the specific to the populational level

Tremetsberger, Karin

Titre : DNA sequence and fingerprint (AFLP) analyses in the genus Hypochaeris (Asteraceae, Cichorieae) : inference of evolutionary patterns and processes from the specific to the populational level

Auteur : Tremetsberger, Karin

Université de soutenance : Universität Wien

Grade : Dr. rer. nat. 2004

Résumé
Hypochaeris has a disjunct distribution with c. 15 species in the Mediterranean region, Canary Islands, Europe and Asia, and > 40 species in South America. The aim of the thesis was to elucidate phylogenetic relationships and investigate infraspecific populational structures. Hypochaeris probably originated in the Mediterranean region. Hypochaeris angustifolia from the Middle Atlas (Morocco) is sister to the monophyletic South American group (dispersal from northwestern Africa across the Atlantic Ocean). The age of divergence between Asteroideae and Cichorioideae s. str. (estimated at 25 million years ago) served as calibration point for the estimation of the age of Hypochaeris. The molecular clock points at an origin of Hypochaeris at the end of Miocene (dispersal to South America during Pliocene or Pleistocene). The fingerprint technique Amplified Fragment Length Polymorphism (AFLP) was used to resolve phylogenetic relationships among the South American species. Hypochaeris seems to have colonised all parts of the continent except the tropical regions immediately after its arrival in South America. AFLP was also used at infraspecific levels in H. acaulis, H. palustris and H. tenuifolia to assess the effect of Pleistocene glaciations and volcanism on the populational structures in the southern Andes. The Chilean Coastal Cordillera served as refugium for H. palustris during the last Pleistocene glaciation. The Andes seem to have been recolonized from nearby refugia at the edges of the glaciers. Genetically differentiated immigrants and rapid population growth on primary lava fields seem to contribute to the augmentation of genetic variability in the pioneer H. tenuifolia.

Mots clés : Systematik / Evolution / Compositae / Südamerika / Biogeographie / Phylogeographie / Vulkanismus / Pleistozän / Internal Transcribed Spacer (ITS) / Amplified Fragment Length Polymorphism (AFLP) — systematics / evolution / compositae / South America / biogeography / phylogeography / volcanism / pleistocene / Internal Transcribed Spacer (ITS) / Amplified Fragment Length Polymorphism (AFLP)

Présentation (österreichischen Bibliothekenverbundes)

Page publiée le 2 décembre 2015, mise à jour le 14 mars 2019