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.

Isozyme Studies on the Dryopteris "spinulosa" Complex, I: The Origin of the Log Fern Dryopteris celsa

Charles R. Werth
Systematic Botany
Vol. 16, No. 3 (Jul. - Sep., 1991), pp. 446-461
DOI: 10.2307/2419336
Stable URL: http://www.jstor.org/stable/2419336
Page Count: 16
  • Read Online (Free)
  • Download ($12.00)
  • 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.
Isozyme Studies on the Dryopteris "spinulosa" Complex, I: The Origin of the Log Fern Dryopteris celsa
Preview not available

Abstract

Most of the species in the genus Dryopteris of eastern North America, as well as several European species, are implicated in an intricate hybrid/polyploid complex referred to here as the D. "spinulosa" complex. Conflicting hypotheses have been proposed to account for the ancestry of the allopolyploid species of this complex: 1) the "semicristata" scheme invokes a hypothetical diploid, putatatively extinct, as an ancestor of certain alloploids; 2) the reinterpretation scheme interprets all all alloploids as derived from extant diploids. To test these hypotheses, a comparative study of isozymes among the species comprising the D. "spinulosa" complex has been undertaken. The present paper reports evidence relative to the origin of the allotetraploid D. celsa, a widespread but locally occurring wetland species. The parentage of D. celsa has been alternatively hypothesized as either D. ludoviciana x goldiana ("semicristata" scheme) or D. ludoviciana x marginalis (reinterpretation scheme). Isozyme patterns were compared for 12 enzymes coded by 19 loci resolved and interpreted across the four relevant species. The inferred isozyme genotype of all D. celsa individuals examined was identical, with rare exceptions, and was homozygous for 13 loci and fixed heterozygous for seven loci. Under the assumption that D. ludoviciana is one ancestor of D. celsa (as both hypotheses agree), all loci were consistent with the hypothesis that D. goldiana was the other ancestor, whereas only 12 were in any way consistent with ancestry by D. marginalis. The assumption of ancestry by D. ludoviciana was supported by all loci except Pgi-2, where D. celsa is fixed for an allele not detected in any of the putative parents. While the origin of this orphan allele is uncertain, its fixation in D. celsa suggests that this allopolyploid species has had a unique origin, in contrast to the multiple origins inferred for other allopolyploid species. This study has provided unequivocal evidence that the ancestry of D. celsa is D. goldiana x ludoviciana, a result that substantially strengthens the plausibility of the "semicristata" scheme.

Page Thumbnails

  • Thumbnail: Page 
446
    446
  • Thumbnail: Page 
447
    447
  • Thumbnail: Page 
448
    448
  • Thumbnail: Page 
449
    449
  • Thumbnail: Page 
450
    450
  • Thumbnail: Page 
451
    451
  • Thumbnail: Page 
452
    452
  • Thumbnail: Page 
453
    453
  • Thumbnail: Page 
454
    454
  • Thumbnail: Page 
455
    455
  • Thumbnail: Page 
[456]
    [456]
  • Thumbnail: Page 
457
    457
  • Thumbnail: Page 
458
    458
  • Thumbnail: Page 
459
    459
  • Thumbnail: Page 
460
    460
  • Thumbnail: Page 
461
    461