South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics

The systematic identity of Senecio madagascariensis is ratified against the opinion that it is conspecific with Senecio inaequidens. Both species are native to South Africa and have been merged in the 'Senecio inaequidens complex', a group of entities difficult to distinguish from each oth...

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Detalles Bibliográficos
Autores principales: López, Mariana G., Wulff, Arturo F., Poggio, Lidia, Xifreda, Cecilia Carmen
Formato: Articulo
Lenguaje:Inglés
Publicado: 2008
Materias:
Ciencias Naturales
Basic chromosome number
Hybridization
Karyotype
Meiotic analysis
Polyploidy
Secondary association of bivalents
Senecio inaequidens
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/82721
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-82721
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Basic chromosome number
Hybridization
Karyotype
Meiotic analysis
Polyploidy
Secondary association of bivalents
Senecio inaequidens
spellingShingle Ciencias Naturales
Basic chromosome number
Hybridization
Karyotype
Meiotic analysis
Polyploidy
Secondary association of bivalents
Senecio inaequidens
López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
topic_facet Ciencias Naturales
Basic chromosome number
Hybridization
Karyotype
Meiotic analysis
Polyploidy
Secondary association of bivalents
Senecio inaequidens
description The systematic identity of Senecio madagascariensis is ratified against the opinion that it is conspecific with Senecio inaequidens. Both species are native to South Africa and have been merged in the 'Senecio inaequidens complex', a group of entities difficult to distinguish from each other. Senecio madagascariensis is widespread in South America and Australia, where it is an invasive weed. Mitotic and meiotic studies were conducted on Argentinian material; chromosome counts solved the chromosome number controversy, validating 2n = 20. The karyotype was symmetrical, composed of ten pairs of metacentric chromosomes varying from 1.62 to 2.38 μm in length. The most frequent number of satellited chromosomes was three, but their position was difficult to assign. Meiosis was regular, with a configuration of ten predominantly open bivalents. Univalents and quadrivalents were rarely observed. High frequencies of secondary associations of bivalents, chromosome asynchrony and bivalent grouping were documented, reinforcing the hypothesis that x = 5 is the basic chromosome number. Pollen stainability ranged from 94 to 99%. The relevance of chromosomal studies in the circumscription of S. madagascariensis is discussed. Hybridization and polyploidy, as principal evolutionary forces in this genus, explain the systematic difficulties.
format Articulo
Articulo
author López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
author_facet López, Mariana G.
Wulff, Arturo F.
Poggio, Lidia
Xifreda, Cecilia Carmen
author_sort López, Mariana G.
title South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
title_short South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
title_full South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
title_fullStr South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
title_full_unstemmed South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics
title_sort south african fireweed senecio madagascariensis (asteraceae) in argentina: relevance of chromosome studies to its systematics
publishDate 2008
url http://sedici.unlp.edu.ar/handle/10915/82721
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