eMonocot Cyperaceae

an authoritative resource for Cyperaceae data worldwide, integrating global and regional perspectives

Karyotype stability and predictors of chromosome number variation in sedges: A study in Carex section Spirostachyae (Cyperaceae)

Publication Type:Journal Article
Year of Publication:2010
Authors:Escudero, M., Hipp, A. L., Luceño M.
Journal:Molecular Phylogenetics and Evolution
Keywords:acutae, Carex, chromosome evolution, europe, evolution, GENUS CAREX, history, holocentric chromosomes, linear models, meiosis, north-african, phylogenetic generalized least squares (gls), phylogenetic heritability, phylogenetic-relationships, rates, spirostachyae

Previous work on holocentric chromosomes in the angiosperm genus Carex demonstrates that many of the traditional sections are marked by different ranges of chromosome number, suggesting phylogenetic autocorrelation. It has been hypothesized that shifting constraints on chromosome rearrangements may limit the potential for hybridization among lineages, promoting speciation. In this study, we evaluated alternative evolutionary models to test for such transitions in Carex section Spirostachyae as well as the relative effects of several plausible drivers of intraspecific chromosome diversity. Chromosome number variation in section Spirostachyae shows significant phylogenetic signal, but no evidence of clade-specific shifts in chromosome number distribution. This gradual model of chromosome evolution contrasts with the shifting equilibrium model previously identified in a younger section of the same genus, suggesting that section Spirostachyae may have a more slowly evolving karyotype. Chromosome number variance, on the other hand, exhibits low phylogenetic signal. Average time of coalescence rather than geographic range Or chromosome number itself predicts chromosome number variance, demonstrating a previously unreported relationship between population history and cytogenetic variation. (C) 2010 Elsevier Inc. All rights reserved.

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