Karyotype evolution in South American species of Hypochaeris (Asteraceae, Lactuceae)

The genus Hypochaeris (Asteraceae, Lactuceae) contains ten species in Europe, three in Asia, and approximately 50 in South America. Previous cytotaxonomic studies have shown two groups of taxa: (1) European species with different basic chromosome numbers and differentiated karyotypes, and (2) South...

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Bibliographic Details
Published in:Plant systematics and evolution 2003-11, Vol.241 (3/4), p.171-184
Main Authors: Weiss-Schneeweiss, H., Stuessy, T. F., Siljak-Yakovlev, S., Baeza, C. M., Parker, J.
Format: Article
Language:English
Subjects:
Asteraceae
Biological evolution
Biological taxonomies
Chromosome 2
Chromosome 3
Chromosome morphology
Chromosomes
Deactivation
Evolution
Fish
Genetic loci
Hypochaeris
Inactivation
Karyotype
Karyotypes
Localization
Nucleoli
Plants
Position (location)
Ribosomal DNA
Species
Taxa
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Summary:The genus Hypochaeris (Asteraceae, Lactuceae) contains ten species in Europe, three in Asia, and approximately 50 in South America. Previous cytotaxonomic studies have shown two groups of taxa: (1) European species with different basic chromosome numbers and differentiated karyotypes, and (2) South American species with x = 4 and uniform asymmetric and bimodal karyotypes. Karyotypic data are synthesized for South American species of Hypochaeris with new information for six Chilean species: H. acaulis, H. apargioides, H. palustris, H. spathulata, H. tenuifolia and H. thrincioides. Four main groups can be distinguished based on presence and localization of secondary constrictions — SCs (bearing Nucleolar Organizer Regions — NORs) on chromosomes 2 and 3, and 18S—25S and 5S rDNA loci number, localization, and activity. We propose karyotypic evolution of South American Hypochaeris (x = 4) from H. maculata-like (x = 5) European ancestors. The original South American karyotype would have possessed two SCs, one on the long arm of chromosome 2, and the other on the short arm of chromosome 3 (in terminal position). Further evolution would have involved inversion within the short arm of chromosome 3 and inactivation/ loss of the SC on chromosome 2.
ISSN:0378-2697
1615-6110
2199-6881
DOI:10.1007/s00606-003-0026-x