Genome size stability despite high chromosome number variation in Carex gr. laevigata
2015
Escudero, Marcial | Maguilla, Enrique | Loureiro, Joäo | Castro, Mariana | Castro, Silvia | Luceño, Modesto
hypothesized to be a result of fi ssion, fusion, and/or translocation events. Negative, positive, or the absence of correlations have been found between chromosome number and genome size in Carex . • Methods: 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. • Key results: Our results show a signifi cant 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. • Conclusions: Our results refi ne 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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