Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Seed Plant Relationships and the Systematic Position of Gnetales Based on Nuclear and Chloroplast DNA: Conflicting Data, Rooting Problems, and the Monophyly of Conifers

Catarina Rydin, Mari Källersjö and Else Marie Friis
International Journal of Plant Sciences
Vol. 163, No. 2 (March 2002), pp. 197-214
DOI: 10.1086/338321
Stable URL: http://www.jstor.org/stable/10.1086/338321
Page Count: 18
  • Read Online (Free)
  • Download ($19.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Seed Plant Relationships and the Systematic Position of Gnetales Based on Nuclear and Chloroplast DNA: Conflicting Data, Rooting Problems, and the Monophyly of Conifers
Preview not available

Abstract

We investigated the systematic position of Gnetales and other seed plant groups using molecular data from 119 land plant species. More than 100 new sequences of rbcL, atpB, 26S, and 18S ribosomal DNA were analyzed together with available GenBank sequences. To evaluate thoroughly the phylogenetic information of each gene, the four data sets were analyzed both separately and combined using different character coding. We found no supported conflict between codon positions in the plastid sequences, but we found a more complex pattern, indicating conflict between transitions and transversions, within each position. Including all information, plastid data results in a “Gnetales basal” phylogeny, whereas nuclear data weakly supports anthophytes. When transitions are excluded, Gnetales associate with conifers. Our study does not answer all questions on seed plant phylogeny, but it does show conifers as monophyletic with high support, rejecting a close relationship between Gnetales and the conifer family Pinaceae. Nuclear and chloroplast data produced essentially identical phylogenies except for the position of the seed plant root, and a sister relationship between Gnetales and angiosperms could not be fully ruled out. These results strongly conflict with previously published analyses of mitochondrial data.

Page Thumbnails

  • Thumbnail: Page 
1
    1
  • Thumbnail: Page 
2
    2
  • Thumbnail: Page 
3
    3
  • Thumbnail: Page 
4
    4
  • Thumbnail: Page 
5
    5
  • Thumbnail: Page 
6
    6
  • Thumbnail: Page 
7
    7
  • Thumbnail: Page 
8
    8
  • Thumbnail: Page 
9
    9
  • Thumbnail: Page 
10
    10
  • Thumbnail: Page 
11
    11
  • Thumbnail: Page 
12
    12
  • Thumbnail: Page 
13
    13
  • Thumbnail: Page 
14
    14
  • Thumbnail: Page 
15
    15
  • Thumbnail: Page 
16
    16
  • Thumbnail: Page 
17
    17
  • Thumbnail: Page 
18
    18