Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Ecological and Evolutionary Opportunities of Apomixis: Insights from Taraxacum and Chondrilla

Peter J. van Dijk
Philosophical Transactions: Biological Sciences
Vol. 358, No. 1434, Mechanisms Regulating Gene Flow in Flowering Plants (Jun. 29, 2003), pp. 1113-1121
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/3558255
Page Count: 9
  • Read Online (Free)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Ecological and Evolutionary Opportunities of Apomixis: Insights from Taraxacum and Chondrilla
Preview not available

Abstract

The ecological and evolutionary opportunities of apomixis in the short and the long term are considered, based on two closely related apomictic genera: Taraxacum (dandelion) and Chondrilla (skeleton weed). In both genera apomicts have a wider geographical distribution than sexuals, illustrating the short-term ecological success of apomixis. Allozymes and DNA markers indicate that apomictic populations are highly polyclonal. In Taraxacum, clonal diversity can be generated by rare hybridization between sexuals and apomicts, the latter acting as pollen donors. Less extensive clonal diversity is generated by mutations within clonal lineages. Clonal diversity may be maintained by frequency-dependent selection, caused by biological interactions (e.g. competitors and pathogens). Some clones are geographically widespread and probably represent phenotypically plastic 'general-purpose genotypes'. The long-term evolutionary success of apomictic clones may be limited by lack of adaptive potential and the accumulation of deleterious mutations. Although apomictic clones may be considered as 'evolutionary dead ends', the genes controlling apomixis can escape from degeneration and extinction via pollen in crosses between sexuals and apomicts. In this way, apomixis genes are transferred to a new genetic background, potentially adaptive and cleansed from linked deleterious mutations. Consequently, apomixis genes can be much older than the clones they are currently contained in. The close phylogenetic relationship between Taraxacum and Chondrilla and the similarity of their apomixis mechanisms suggest that apomixis in these two genera could be of common ancestry.

Page Thumbnails

  • Thumbnail: Page 
1113
    1113
  • Thumbnail: Page 
1114
    1114
  • Thumbnail: Page 
1115
    1115
  • Thumbnail: Page 
1116
    1116
  • Thumbnail: Page 
1117
    1117
  • Thumbnail: Page 
1118
    1118
  • Thumbnail: Page 
1119
    1119
  • Thumbnail: Page 
1120
    1120
  • Thumbnail: Page 
1121
    1121