Radiation of the endemic genus Dendroseris (Asteraceae) on the Juan Fernandez Islands: evidence from sequences of the ITS regions of nuclear ribosomal DNA

Phylogenetic relationships among nine of the 11 species of the endemic genus Dendroseris on the Juan Fernandez Islands were inferred from nucleotide sequences of the internal transcribed spacer regions (ITS) of the 18-26S nuclear ribosomal DNA. Sequences were determined for 15 populations of Dendros...

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Bibliographic Details
Published in:American journal of botany 1994-11, Vol.81 (11), p.1494-1501
Main Authors: Sang, T. (Ohio State University, Columbus, OH.), Crawford, D.J, Kim, S.C, Stuessy, T.F
Format: Article
Language:English
Subjects:
ADN
Biological taxonomies
Botany
CHILE
CHILI
Classification
COMPOSITAE
Deoxyribonucleic acid
DISTRIBUCION NATURAL
DISTRIBUTION NATURELLE
DNA
Evolution
FILOGENIA
FLORA
FLORE
Genera
Genetic mutation
GENETICA
Genetics
GENETIQUE
Internal transcribed spacers
NOYAU CELLULAIRE
NUCLEO
PHYLOGENIE
Phylogeny
Plants
Ribosomal DNA
RIBOSOMAS
RIBOSOME
SECUENCIA NUCLEICA
SEQUENCE NUCLEIQUE
Systematics and Evolution
Taxa
TAXONOMIA
TAXONOMIE
VARIACION GENETICA
VARIATION GENETIQUE
We they distinction
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Summary:Phylogenetic relationships among nine of the 11 species of the endemic genus Dendroseris on the Juan Fernandez Islands were inferred from nucleotide sequences of the internal transcribed spacer regions (ITS) of the 18-26S nuclear ribosomal DNA. Sequences were determined for 15 populations of Dendroseris and one population for each of two outgroups from the genera Sonchus and Sventenia. Little length variation was detected in the ITS regions of Dendroseris, with ITS 1 253 or 254 bp long and ITS 2 224 or 225 bp. The sequence data provide strong support for the holophyly of Dendroseris despite the distinct morphological differences among the three subgenera. The molecular data also indicate that subg. Dendroseris and Phoenicoseris are holophyletic, but do not support holophyly of subg. Rea. The ITS sequences did not resolve relationships among subgenera, supporting the hypothesis of rapid adaptive radiation of Dendroseris on the islands. Relative rate tests indicate that rates of nucleotide substitutions in the ITS regions are not significantly different among the different lineages of Dendroseris following adaptive radiation. Comparisons of average pairwise sequence divergence of Dendroseris species in the ITS regions and chloroplast genome indicated that ITS sequences have evolved about 38 times faster than cpDNA in the genus. Rates of ITS sequence divergence of Dendroseris were estimated to be faster than (3.94 +/- 0.10) X 10(-9) per site per year, and likely (6.06 +/- 0.15) X 10(-9) per site per year
ISSN:0002-9122
1537-2197
DOI:10.1002/j.1537-2197.1994.tb15635.x