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ndhF Sequence Evolution and the Major Clades in the Sunflower Family

Ki-Joong Kim and Robert K. Jansen
Proceedings of the National Academy of Sciences of the United States of America
Vol. 92, No. 22 (Oct. 24, 1995), pp. 10379-10383
Stable URL: http://www.jstor.org/stable/2368679
Page Count: 5
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
ndhF Sequence Evolution and the Major Clades in the Sunflower Family
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Abstract

An extensive sequence comparison of the chloroplast ndhF gene from all major clades of the largest flowering plant family (Asteraceae) shows that this gene provides $\thickapprox$3 times more phylogenetic information than rbcL. This is because it is substantially longer and evolves twice as fast. The 5' region (1380 bp) of ndhF is very different from the 3' region (855 bp) and is similar to rbcL in both the rate and the pattern of sequence change. The 3' region is more A+T-rich, has higher levels of nonsynonymous base substitution, and shows greater transversion bias at all codon positions. These differences probably reflect different functional constraints on the 5' and 3' regions of ndhF. The two patterns of base substitutions of ndhF are particularly advantageous for phylogenetic reconstruction because the conserved and variable segments can be used for older and recent groups, respectively. Phylogenetic analyses of 94 ndhF sequences provided much better resolution of relationships than previous molecular and morphological phylogenies of the Asteraceae. The ndhF tree identified five major clades: (i) the Calyceraceae is the sister family of Asteraceae; (ii) the Barnadesioideae is monophyletic and is the sister group to the rest of the family; (iii) the Cichorioideae and its two basal tribes Mutisieae and Cardueae are paraphyletic; (iv) four tribes of Cichorioideae (Lactuceae, Arctoteae, Liabeae, and Vernonieae) form a monophyletic group, and these are the sister clade of the Asteroideae; and (v) the Asteroideae is monophyletic and includes three major clades.

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