Cytotype stability, facultative apomixis and geographical parthenogenesis in Ranunculus kuepferi (Ranunculaceae)
Open Access
- 24 January 2010
- journal article
- research article
- Published by Oxford University Press (OUP) in Annals of Botany
- Vol. 105 (3), 457-470
- https://doi.org/10.1093/aob/mcp304
Abstract
Asexual organisms are more widespread in previously glaciated areas than their sexual relatives (‘geographical parthenogenesis’). In plants, this pattern is probably dependent on reproductive isolation and stability of cytotypes within their respective distribution areas. Both partial apomixis and introgressive hybridization potentially destabilize the spatial separation of sexual and apomictic populations. The wide distribution of apomicts may be further enhanced by uniparental reproduction which is advantageous for colonization. These factors are studied in the alpine species Ranunculus kuepferi. Geographical distribution, diversity and mode of reproduction of cytotypes were assessed using flow cytometry and flow cytometric seed screening on samples from 59 natural populations of Ranunculus kuepferi. Seed set of cytotypes was compared in the wild. Diploid sexuals are confined to the south-western parts of the Alps, while tetraploid apomicts dominate in previously glaciated and in geographically isolated areas despite a significantly lower fertility. Other cytotypes (3x, 5x and 6x) occur mainly in the sympatric zone, but without establishing populations. The tetraploids are predominantly apomictic, but also show a partial apomixis via an uncoupling of apomeiosis and parthenogenesis in the seed material. Both pseudogamy and autonomous endosperm formation are observed which may enhance uniparental reproduction. Diploids occupy a glacial relic area and resist introgression of apomixis, probably because of a significantly higher seed set. Among the polyploids, only apomictic tetraploids form stable populations; the other cytotypes arising from partial apomixis fail to establish, probably because of minority cytotype disadvantages. Tetraploid apomicts colonize previously devastated and also distant areas via long-distance dispersal, confirming Baker's law of an advantage of uniparental reproduction. It is concluded that stability of cytotypes and of modes of reproduction are important factors for establishing a pattern of geographical parthenogenesis.Keywords
This publication has 54 references indexed in Scilit:
- The evolution of self-fertility in apomictic plantsSexual Plant Reproduction, 2009
- Introgression of apomixis into sexual species is inhibited by mentor effects and ploidy barriers in the Ranunculus auricomus complexAnnals of Botany, 2009
- Understanding the geographic distributions of apomictic plants: a case for a pluralistic approachPlant Ecology & Diversity, 2008
- Evolutionary Implications of Self‐Compatibility and Reproductive Fitness in the ApomicticRanunculus auricomusPolyploid Complex (Ranunculaceae)International Journal of Plant Sciences, 2008
- Cytogeography of Pilosella officinarum (Compositae): Altitudinal and Longitudinal Differences in Ploidy Level Distribution in the Czech Republic and Slovakia and the General Pattern in EuropeAnnals of Botany, 2007
- Cytochemistry and C-values: The Less-well-known World of Nuclear DNA AmountsAnnals of Botany, 2007
- Glacialin situsurvival in the Western Alps and polytopic autopolyploidy inBiscutella laevigataL. (Brassicaceae)Molecular Ecology, 2007
- The complex causality of geographical parthenogenesisNew Phytologist, 2006
- The role of hybridization, polyploidization and glaciation in the origin and evolution of the apomicticRanunculus cassubicuscomplexNew Phytologist, 2006
- The advantages and disadvantages of being polyploidNature Reviews Genetics, 2005