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Genome size stability despite high chromosome number variation in Carex gr. laevigata

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2015-02-02
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Wiley
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In organisms with holocentric chromosomes like Carex species, chromosome number evolution has been hypothesized to be a result of fission, fusion, and/or translocation events. Negative, positive, or the absence of correlations have been found between chromosome number and genome size in Carex. Using the inferred diploid chromosome number and 80 genome size measurements from 26 individuals and 20 populations of Carex gr. laevigata, we tested the null hypothesis of chromosome number evolution by duplication and deletion of whole chromosomes. Our results show a significant positive correlation between genome size and chromosome number, but the slope of such correlation supports the hypothesis of proliferation and removal of repetitive DNA fragments to explain genome size variation rather than duplication and deletion of whole chromosomes. Our results refine the theory of the holokinetic drive: this mechanism is proposed to facilitate repetitive DNA removal (or any segmental deletion) when smaller homologous chromosomes are preferentially inherited, or repetitive DNA proliferation (or any segmental duplication) when larger homologs are preferred. This study sheds light on how karyotype evolution plays an important role in the diversification of the species of the genus Carex.
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info:eu-repo/grantAgreement/MINECO//CGL2012-38744/ES/POR QUE ES CAREX (CYPERACEAE) UN GENERO MEGADIVERSO? UNA APROXIMACION FILOGENETICA Y EVOLUTIVA PARA UNA PREGUNTA COMPLEJA/
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This article was supported by a grant funded by the Spanish government and the European Commission (CGL2012-38744) to ML (PI), ME, and EM, and also by a postdoctoral 2011 Marie Curie IOF (HoloChromEvol 301119) to ME. The Portuguese Foundation for Science and Technology funded the work of SC (IF/01267/2013) and MC (FCT/SFRH/BD/89617/2012).
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American Journal of Botany, vol 102, nº2, p. 233-238
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