Journal Article

Chromosome evolution in marginal populations of <i>Aegilops speltoides</i>: causes and consequences

Alexander Belyayev and Olga Raskina

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 111, issue 4, pages 531-538
Published in print April 2013 | ISSN: 0305-7364
Published online February 2013 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mct023
Chromosome evolution in marginal populations of Aegilops speltoides: causes and consequences

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

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Background

Genome restructuring is an ongoing process in natural plant populations. The influence of environmental changes on the genome is crucial, especially during periods of extreme climatic fluctuations. Interactions between the environment and the organism manifest to the greatest extent at the limits of the species' ecological niche. Thus, marginal populations are expected to exhibit lower genetic diversity and higher genetic differentiation than central populations, and some models assume that marginal populations play an important role in the maintenance and generation of biological diversity.

Scope

In this review, long-term data on the cytogenetic characteristics of diploid Aegilops speltoides Tauch populations are summarized and discussed. This species is distributed in and around the Fertile Crescent and is proposed to be the wild progenitor of a number of diploid and polyploid wheat species. In marginal populations of Ae. speltoides, numerical chromosomal aberrations, spontaneous aneuploidy, B-chromosomes, rDNA cluster repatterning and reduction in the species-specific and tribe-specific tandem repeats have been detected. Significant changes were observed and occurred in parallel with changes in plant morphology and physiology.

Conclusions

Considerable genomic variation at the chromosomal level was found in the marginal populations of Ae. speltoides. It is likely that a specific combination of gene mutations and chromosomal repatterning has produced the evolutionary trend in each specific case, i.e. for a particular species or group of related species in a given period of time and in a certain habitat. The appearance of a new chromosomal pattern is considered an important factor in promoting the emergence of interbreeding barriers.

Keywords: Aegilops speltoides; wheat; marginal populations; chromosomes; evolution; speciation

Journal Article.  4893 words.  Illustrated.

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

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