TITLE	Molecular evolution of the atpB-rbcL noncoding spacer of chloroplast DNA in the moss family Hylocomiaceae
AUTHOR	Tzen-Yuh Chiang Department of Biology, Cheng-Kung University, Tainan 700, Taiwan Barbara A. Schaal Department of Biology, Washington University, St. Louis, MO 63130, USA
FULL TEXT	[in HTML format] [in PDF format]
ABSTRACT	Molecular evolution of the chloroplast noncoding region between the atpB and rbcL genes was investigated in the moss family Hylocomiaceae. Nucleotide substitution contributed to most of the variation among taxa, although an insertion of 29 base pairs was found in Rhytidiopsis robusta. The evolution of atpB-rbcL intergenic spacer was constrained in Hylocomiaceae compared to the evolutionary rates of this chloroplast spacer, and even of the rbcL gene, in angiosperms. Using a relative rate test procedure, substitution rates of the chloroplast spacer were found to be consistent with the hypothesis of a molecular clock, except for three taxa. Based on previous knowledge of the evolutionary rate of this spacer in true mosses, the divergence of the Hylocomiaceae from their common ancestor was estimated to be 29.0 million years ago, which is consistent with the fossil record. The chloroplast sequences supported the monophyly of the Hylocomiaceae with a bootstrap value of 82%. The effects of long branch attraction caused the erroneous placements of Rhytidiopsis and Rhytidium in the parsimony analysis. In contrast, neighbor-joining analysis provided a more congruent estimate of the phylogeny of the Hylocomiaceae based on the cpDNA variation observed.
KEYWORD	atpB-rbcL intergenic spacer; Chloroplast DNA; DNA sequence; Gene tree; Hylocomiaceae; Long branch attraction; Molecular clock; Mosses;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 41 Number 2 April 2000, page 85-92, 8 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China