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Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbc L and nuclear 18S ribosomal DNA Sequences
Author(s) -
Rivadavia Fernando,
Kondo Katsuhiko,
Kato Masahiro,
Hasebe Mitsuyasu
Publication year - 2003
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.90.1.123
Subject(s) - biology , botany , clade , phylogenetic tree , chloroplast dna , polyphyly , genus , phylogenetics , ribosomal dna , gene , genetics
The sundew genus Drosera consists of carnivorous plants with active flypaper traps and includes nearly 150 species distributed mainly in Australia, Africa, and South America, with some Northern Hemisphere species. In addition to confused intrageneric classification of Drosera , the intergeneric relationships among the Drosera and two other genera in the Droseraceae with snap traps, Dionaea and Aldrovanda , are problematic. We conducted phylogenetic analyses of DNA sequences of the chloroplast rbcL gene for 59 species of Drosera , covering all sections except one. These analyses revealed that five of 11 sections, including three monotypic sections, are polyphyletic. Combined rbcL and 18S rDNA sequence data were used to infer phylogenetic relationships among Drosera , Dionaea , and Aldrovanda . This analysis revealed that all Drosera species form a clade sister to a clade including Dionaea and Aldrovanda , suggesting that the snap traps of Aldrovanda and Dionaea are homologous despite their morphological differences. MacClade reconstructions indicated that multiple episodes of aneuploidy occurred in a clade that includes mainly Australian species, while the chromosome numbers in the other clades are not as variable. Drosera regia , which is native to South Africa, and most species native to Australia, were clustered basally, suggesting that Drosera originated in Africa or Australia. The rbcL tree indicates that Australian species expanded their distribution to South America and then to Africa. Expansion of distribution to the Northern Hemisphere from the Southern Hemispere occurred in a few different lineages.