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Genome size stability despite high chromosome number variation in Carex gr. laevigata
Author(s) -
Escudero Marcial,
Maguilla Enrique,
Loureiro João,
Castro Mariana,
Castro Sílvia,
Luceño Modesto
Publication year - 2015
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1400433
Subject(s) - biology , genome size , chromosome , carex , genetics , genome , ploidy , karyotype , gene duplication , segmental duplication , homologous chromosome , genome evolution , chromosome 16 , evolutionary biology , gene , botany , gene family
• Premise of the study: 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 . • 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 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. • Conclusions: 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 .