Chromosomes tell half of the story: the correlation between karyotype rearrangements and genetic diversity in sedges, a group with holocentric chromosomes

  1. ANDREW L. HIPP1,2,
  2. PAUL E. ROTHROCK3,
  3. RICHARD WHITKUS4,
  4. JAIME A. WEBER1

Article first published online: 8 JUL 2010

DOI: 10.1111/j.1365-294X.2010.04741.x

Issue

Molecular Ecology

Molecular Ecology

Volume 19, Issue 15, pages 3124–3138, August 2010

Additional Information

How to Cite

HIPP, A. L., ROTHROCK, P. E., WHITKUS, R. and WEBER, J. A. (2010), Chromosomes tell half of the story: the correlation between karyotype rearrangements and genetic diversity in sedges, a group with holocentric chromosomes. Molecular Ecology, 19: 3124–3138. doi: 10.1111/j.1365-294X.2010.04741.x

Author Information

  1. 1

    The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL 60532-1293, USA

  2. 2

    The Field Museum, 1400 S. Lakeshore Drive, Chicago, IL 60605, USA

  3. 3

    Taylor University, Randall Environmental Studies Center, Upland, IN 46989-1001, USA

  4. 4

    Department of Biology, Sonoma State University, Rohnert Park, CA 94928-3613, USA

*Andrew L. Hipp, Fax: +1 630 719 2433; E-mail: ahipp@mortonarb.org

Publication History

  1. Issue published online: 20 JUL 2010
  2. Article first published online: 8 JUL 2010
  3. Received 15 January 2010; revision received 24 March 2010; accepted 26 March 2010

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Keywords:

  • amplified fragment length polymorphisms;
  • Carex;
  • chromosome rearrangements;
  • Cyperaceae;
  • holocentric chromosomes;
  • karyotype evolution

Abstract

Chromosome rearrangements may affect the rate and patterns of gene flow within species, through reduced fitness of structural heterozygotes or by reducing recombination rates in rearranged areas of the genome. While the effects of chromosome rearrangements on gene flow have been studied in a wide range of organisms with monocentric chromosomes, the effects of rearrangements in holocentric chromosomes—chromosomes in which centromeric activity is distributed along the length of the chromosome—have not. We collected chromosome number and molecular genetic data in Carex scoparia, an eastern North American plant species with holocentric chromosomes and highly variable karyotype (2n = 56–70). There are no deep genetic breaks within C. scoparia that would suggest cryptic species differentiation. However, genetic distance between individuals is positively correlated with chromosome number difference and geographic distance. A positive correlation is also found between chromosome number and genetic distance in the western North American C. pachystachya (2n = 74–81). These findings suggest that geographic distance and the number of karyotype rearrangements separating populations affect the rate of gene flow between those populations. This is the first study to quantify the effects of holocentric chromosome rearrangements on the partitioning of intraspecific genetic variance.

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