Journal Article

High ploidy diversity and distinct patterns of cytotype distribution in a widespread species of <i>Oxalis</i> in the Greater Cape Floristic Region

Jana Krejčíková, Radka Sudová, Magdalena Lučanová, Pavel Trávníček, Tomáš Urfus, Petr Vít, Hanna Weiss-Schneeweiss, Bożena Kolano, Kenneth Oberlander, Leanne L. Dreyer and Jan Suda

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 111, issue 4, pages 641-649
Published in print April 2013 | ISSN: 0305-7364
Published online February 2013 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mct030
High ploidy diversity and distinct patterns of cytotype distribution in a widespread species of Oxalis in the Greater Cape Floristic Region

More Like This

Show all results sharing these subjects:

  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

Background and Aims

Genome duplication is widely acknowledged as a major force in the evolution of angiosperms, although the incidence of polyploidy in different floras may differ dramatically. The Greater Cape Floristic Region of southern Africa is one of the world's biodiversity hotspots and is considered depauperate in polyploids. To test this assumption, ploidy variation was assessed in a widespread member of the largest geophytic genus in the Cape flora: Oxalis obtusa.

Methods

DNA flow cytometry complemented by confirmatory chromosome counts was used to determine ploidy levels in 355 populations of O. obtusa (1014 individuals) across its entire distribution range. Ecological differentiation among cytotypes was tested by comparing sets of vegetation and climatic variables extracted for each locality.

Key Results

Three majority (2x, 4x, 6x) and three minority (3x, 5x, 8x) cytotypes were detected in situ, in addition to a heptaploid individual originating from a botanical garden. While single-cytotype populations predominate, 12 mixed-ploidy populations were also found. The overall pattern of ploidy level distribution is quite complex, but some ecological segregation was observed. Hexaploids are the most common cytotype and prevail in the Fynbos biome. In contrast, tetraploids dominate in the Succulent Karoo biome. Precipitation parameters were identified as the most important climatic variables associated with cytotype distribution.

Conclusions

Although it would be premature to make generalizations regarding the role of genome duplication in the genesis of hyperdiversity of the Cape flora, the substantial and unexpected ploidy diversity in Oxalis obtusa is unparalleled in comparison with any other cytologically known native Cape plant species. The results suggest that ploidy variation in the Greater Cape Floristic Region may be much greater than currently assumed, which, given the documented role of polyploidy in speciation, has direct implications for radiation hypotheses in this biodiversity hotspot.

Keywords: Cape Floristic Region; cytogeography; flow cytometry; Fynbos; Oxalis obtusa; polyploidy; Succulent Karoo; vegetation

Journal Article.  5511 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.