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Phylogeny of Isoëtes (Lycopsida): resolving basal relationships using rbcL sequences
Author(s) -
Rydin Catarina,
Wikström Niklas
Publication year - 2002
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.2307/1554965
Subject(s) - cladistics , biology , phylogenetic tree , divergence (linguistics) , phylogenetics , evolutionary biology , morphology (biology) , clade , ecology , zoology , gene , biochemistry , linguistics , philosophy
The phylogenetic relationships of Isoëtes (Isoëtaceae) were investigated by means of a cladistic analysis using plastid rbcL sequences and a representative sample of 18 species. The analysis supports a basal split in Isoëtes separating two main groups, one including aquatic species from South America ( I. bradei and I. amazonica ) and West Africa ( I. kersii and I. schweinfurthii ), and the other including aquatic, amphibious and terrestrial species representing all major continents. Higher level relationships remain unresolved, but supported groups do conflict with previous morphologybased hypotheses. Comparatively low levels of sequence divergence indicate that the use of more rapidly evolving regions will be required to resolve higher level relationships. The phylogenetically isolated nature of Isoëtes will in such analyses make standard outgroup comparisons problematic, and results presented here will in this respect prove important by providing support for choosing among alternative rooting options.