Radiation of the Hypochaeris apargioides complex (Asteraceae: Cichorieae) of southern South America
Radiation into different environments is a common evolutionary phenomenon in plants. This process has been extensively documented in oceanic islands and to a lesser extent in continental areas. The genus Hypochaeris (Asteraceae: Cichorieae) contains 41 species in South America
that have evolved during the past one million years. Dispersal of propagules to new regions followed by speciation at the diploid level into different ecological zones has resulted in radiated groups. One such group, the H. apargioides complex, consists of four closely related species,
H. apargioides, H. gayana, H. spathulata, and H. thrincioides, all of which are distributed in central-south Chile and adjacent Argentina. Morphometric and molecular (AFLP) data were used to help reveal processes involved in the evolution of the complex. A total
of 54 populations were sampled: 34 were analyzed morphometrically and 45 were examined for genetic variation and divergence using AFLP methodology. Mor- phometric analysis shows that two species, H. gayana and H. spathulata, are clearly separated phenotypically from the others,
but that H. apargioides and H. thrincioides are more similar to each other. The principal environmental conditions influencing morphology and distribution of species in the H. apargioides complex appear to be salinity and elevation in H. spathulata and H. gayana,
respectively, and climate in H. apargioides and H. thrincioides. The overall pattern in the evolution of the complex is one of subtle morphological divergence in response to environmental selection, perhaps reflecting initial stages of adaptive radiation. The low level of molecular
divergence among species also suggests rapid speciation.
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Document Type: Research Article
Department of Systematic and Evolutionary Botany, Faculty Center of Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria, Departamento de Botánica, Universidad de Concepción, Casilla 2407,
Institute of Botany, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Life Sciences, Gregor Mendel Straße 33, 1180 Vienna, Austria;, Email: firstname.lastname@example.org
Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apartado de Correos 1095, 41080 Sevilla, España
Departamento de Botánica, Universidad de Concepción, Casilla 2407, Concepción, Chile
Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, 2 Norte 685, Talca, Chile
Department of Systematic and Evolutionary Botany, Faculty Center of Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
Publication date: 2013-06-17
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