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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todo:paper_00244074_v158_n4_p613_Lopez2023-10-03T14:35:05Z South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics López, M.G. Wulff, A.F. Poggio, L. Xifreda, C.C. Basic chromosome number Hybridization Karyotype Meiotic analysis Polyploidy Secondary association of bivalents Senecio inaequidens chromosome conspecific dicotyledon evolutionary biology geographical distribution hybridization invasive species karyotype native species pollen polyploidy taxonomy weed Africa Argentina South Africa South America Southern Africa Sub-Saharan Africa Asteraceae Bassia scoparia Chamerion angustifolium Senecio Senecio inaequidens Senecio madagascariensis 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. © 2008 The Linnean Society of London. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00244074_v158_n4_p613_Lopez |
| institution |
Universidad de Buenos Aires |
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I-28 |
| repository_str |
R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Basic chromosome number Hybridization Karyotype Meiotic analysis Polyploidy Secondary association of bivalents Senecio inaequidens chromosome conspecific dicotyledon evolutionary biology geographical distribution hybridization invasive species karyotype native species pollen polyploidy taxonomy weed Africa Argentina South Africa South America Southern Africa Sub-Saharan Africa Asteraceae Bassia scoparia Chamerion angustifolium Senecio Senecio inaequidens Senecio madagascariensis |
| spellingShingle |
Basic chromosome number Hybridization Karyotype Meiotic analysis Polyploidy Secondary association of bivalents Senecio inaequidens chromosome conspecific dicotyledon evolutionary biology geographical distribution hybridization invasive species karyotype native species pollen polyploidy taxonomy weed Africa Argentina South Africa South America Southern Africa Sub-Saharan Africa Asteraceae Bassia scoparia Chamerion angustifolium Senecio Senecio inaequidens Senecio madagascariensis López, M.G. Wulff, A.F. Poggio, L. Xifreda, C.C. South African fireweed Senecio madagascariensis (Asteraceae) in Argentina: Relevance of chromosome studies to its systematics |
| topic_facet |
Basic chromosome number Hybridization Karyotype Meiotic analysis Polyploidy Secondary association of bivalents Senecio inaequidens chromosome conspecific dicotyledon evolutionary biology geographical distribution hybridization invasive species karyotype native species pollen polyploidy taxonomy weed Africa Argentina South Africa South America Southern Africa Sub-Saharan Africa Asteraceae Bassia scoparia Chamerion angustifolium Senecio Senecio inaequidens Senecio madagascariensis |
| 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. © 2008 The Linnean Society of London. |
| format |
JOUR |
| author |
López, M.G. Wulff, A.F. Poggio, L. Xifreda, C.C. |
| author_facet |
López, M.G. Wulff, A.F. Poggio, L. Xifreda, C.C. |
| author_sort |
López, M.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 |
| url |
http://hdl.handle.net/20.500.12110/paper_00244074_v158_n4_p613_Lopez |
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| _version_ |
1807318246255230976 |