Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in 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.
Journal Article

Reconstruction of the Evolution of Reproductive Characters in Pontederiaceae Using Phylogenetic Evidence from Chloroplast DNA Restriction-Site Variation

Joshua R. Kohn, Sean W. Graham, Brian Morton, Jeff J. Doyle and Spencer C. H. Barrett
Evolution
Vol. 50, No. 4 (Aug., 1996), pp. 1454-1469
DOI: 10.2307/2410883
Stable URL: http://www.jstor.org/stable/2410883
Page Count: 16
Were these topics helpful?
See somethings inaccurate? Let us know!

Select the topics that are inaccurate.

Cancel
  • Read Online (Free)
  • Download ($4.00)
  • Subscribe ($19.50)
  • Add to My Lists
  • 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.
Reconstruction of the Evolution of Reproductive Characters in Pontederiaceae Using Phylogenetic Evidence from Chloroplast DNA Restriction-Site Variation
Preview not available

Abstract

We reconstructed the phylogenetic history of Pontedenaceae using chloroplast DNA restriction-site variation from approximately two-thirds of the species in this family of aquatic monocotyledons. The molecular phylogeny was used to evaluate hypotheses concerning the evolution of reproductive characters associated with the breeding system. The family has four mare genera, two of which (Eichhornia and Pontederia) have tristylous, predominantly outcrossing species, while two (Monochorta and Heteranthera) have enantiostylous taxa. Self-incompatibility is restricted to some but not all tristylous species. In Eichhornia and Pontederia, predominantly selfing species with small monomorphic flowers (homostyly) have been hypothesized to result from the multiple breakdown of tristyly. Restriction-site variation provided a well supported phylogeny of ingroup taxa, enabling the mapping of reproductive characters onto trees. Two contrasting optimization schemes were assessed, differing in the relative weights assigned to shifts in character states. The reconstructed sequence of floral character-state change was used to assess competing hypotheses concerning the origin and breakdown of tristyly, and the relationships between tristylous and enantiostylous syndromes. Our results indicate that the class of optimization scheme used was the most critical factor in reconstructing character evolution. Despite some topological uncertainties and difficulty in reconstructing the primitive floral form in the family, several broad conclusions were possible when an unordered, unequally-weighted optimization scheme was used: (1) tristyly originated either once or twice, while the occurrence of enantiostyly in Monochoria and Heteranthera was always found to have independent origins; (2) tristyly has repeatedly broken down leading to selfing, homostylous taxa; and (3) self-incompatibility probably arose after the origin of floral trimorphism, a sequence of events that conflicts with some evolutionary models.

Page Thumbnails

  • Thumbnail: Page 
1454
    1454
  • Thumbnail: Page 
1455
    1455
  • Thumbnail: Page 
1456
    1456
  • Thumbnail: Page 
1457
    1457
  • Thumbnail: Page 
1458
    1458
  • Thumbnail: Page 
1459
    1459
  • Thumbnail: Page 
1460
    1460
  • Thumbnail: Page 
1461
    1461
  • Thumbnail: Page 
1462
    1462
  • Thumbnail: Page 
1463
    1463
  • Thumbnail: Page 
1464
    1464
  • Thumbnail: Page 
1465
    1465
  • Thumbnail: Page 
1466
    1466
  • Thumbnail: Page 
1467
    1467
  • Thumbnail: Page 
1468
    1468
  • Thumbnail: Page 
1469
    1469