Phylogenetic Implications of Chloroplast DNA Variation in the Cyatheaceae. I.

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ABsTRAcr. Restriction site maps of the chloroplast DNA of four tree ferns (Alsophila bryophila, furfuracea, cooperi, and Lophosoria quadripinnata) have been constructed using four enzymes. Genome sizes were estimated as ranging from 161.8 kilobases for L. quadripinnata to 179.2 kilobases for C. furfuracea, the largest sizes thus far reported for ferns. Evolutionary relationships of 23 species of Cyatheaceae were assessed by comparative chloroplast DNA restriction site mapping. A total of 67 restriction site mutations, 58 of which were phylogenetically informative, was detected using 20 restriction enzymes. Phylogenetic analyses of restriction site mutations were carried out using both Wagner and Dollo parsimony and the resulting monophyletic groups were evaluated by bootstrapping. The data show strong support for three major evolutionary lineages within the family: the Alsophila clade, the clade, and the Sphaeropteris clade. The Alsophila clade appears to be the most basal group in the family whereas the Cyathea and Sphaeropteris clades are derived sister groups. Comparison of these results to the three modern classification systems for the family demonstrates that our findings are most consistent with the system of Lellinger.