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May 2004
editSome of the current phylogenetic research seems to indicate that inclusion of Order Marsileales in the same subclass with the Schizeaceae could be problematic. According to Pryer and Smith, a subclass Schizaeatae that includes the heterosporous ferns and the Schizeaceae could very well be paraphyletic or polyphyletic. They write that "Although the tree ferns, the heterosporous ferns, and the schizaeoid ferns are each well supported clades, their interrelationships (and those of all basal families) remain unresolved." (http://tolweb.org/tree?group=leptosporangiate_ferns&contgroup=Filicopsida)
Perhaps it is better not to assign Marsileales to subclass Schizeatae if it is not well supported.Tom Radulovich 02:04, 18 May 2004 (UTC)
- I understand. The big rbg sequencing indicated this relationship, plus traditional analyses of relationships based on morphology seemed to indicate a relationship between the schizaeoid ferns and the Marsileaceae. jaknouse 02:37, 18 May 2004 (UTC)
- In "Fern Phylogeny based on rbcL Nucleotide Sequences" (American Fern Journal 85(4) 134-181 (1995) Hasebe et. al. write that "9) tree ferns of the Cytheaceae, Metaxyaceae, and Dicksoniaceae form a monophyletic group that emerged early in the diversification of the leptosporangiate ferns; 10) Plagiogyriaceae and Loxomataceae emerge with the tree ferns; 11) heterosporous water ferns form a monophyletic group that diverged prior to the tree ferns; 12) Schizaeaceae, Cheiropleuriaceae, Dipteridaceae, Gleicheniaceae, Matoniaceae, and Hymenophyllaceae are basal to the heterosporous aquatic ferns" (Page 135) and that "The heterosporous ferns are more closely related to the most derived leptosporangiate ferns (including the tree fern group) than they are to the Schizaeaceae. Azollaceae, Salviniaceae, and Marsiliaceae form as strongly supported, monophyletic group." (Page 157). If this is so, then it seems that the Cytheatae is supported as a subclass (including the Cytheaceae, Metaxyaceae, and Dicksoniaceae, and perhaps the Plagiogyriaceae and Loxomataceae), as is a subclass of heterosporous ferns, but that a monophyletic clade which includes both the Schizaeaceae and the heterosporous ferns is not supported by the rbcL sequencing.Tom Radulovich 07:49, 18 May 2004 (UTC)
- Perhaps I misremembered or misread that article. Anyway, I have no problem with removing the Schizaeatae thing. My most important interest here is that including subclasses in the ferns is highly relevant to a proper understanding of their phylogeny. jaknouse 13:33, 18 May 2004 (UTC)
- In "Fern Phylogeny based on rbcL Nucleotide Sequences" (American Fern Journal 85(4) 134-181 (1995) Hasebe et. al. write that "9) tree ferns of the Cytheaceae, Metaxyaceae, and Dicksoniaceae form a monophyletic group that emerged early in the diversification of the leptosporangiate ferns; 10) Plagiogyriaceae and Loxomataceae emerge with the tree ferns; 11) heterosporous water ferns form a monophyletic group that diverged prior to the tree ferns; 12) Schizaeaceae, Cheiropleuriaceae, Dipteridaceae, Gleicheniaceae, Matoniaceae, and Hymenophyllaceae are basal to the heterosporous aquatic ferns" (Page 135) and that "The heterosporous ferns are more closely related to the most derived leptosporangiate ferns (including the tree fern group) than they are to the Schizaeaceae. Azollaceae, Salviniaceae, and Marsiliaceae form as strongly supported, monophyletic group." (Page 157). If this is so, then it seems that the Cytheatae is supported as a subclass (including the Cytheaceae, Metaxyaceae, and Dicksoniaceae, and perhaps the Plagiogyriaceae and Loxomataceae), as is a subclass of heterosporous ferns, but that a monophyletic clade which includes both the Schizaeaceae and the heterosporous ferns is not supported by the rbcL sequencing.Tom Radulovich 07:49, 18 May 2004 (UTC)