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PHYLOGENETIC ANALYSIS OF 32 STRAINS OF VAUCHERIA (XANTHOPHYCEAE) USING THE rbc L GENE AND ITS TWO FLANKING SPACER REGIONS 1
Author(s) -
Andersen Robert A.,
Bailey J. Craig
Publication year - 2002
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1046/j.1529-8817.2002.01144.x
Subject(s) - biology , monophyly , phylogenetic tree , botany , maximum parsimony , clade , internal transcribed spacer , gene , phylogenetics , rubisco , genetics
The complete rbc L gene was sequenced for 21 species and 32 strains of Vaucheria and for five other Xanthophyceae ( Asterosiphon dichotomus (Kützing) Rieth, Botrydium becharianum Vischer, B. cystosum Vischer, B. stoloniferum Mitra, Tribonema intermixtum Pascher). The psb A‐ rbc L spacer, upstream of the rbc L gene, and the RUBISCO spacer between the rbc L and rbc S genes were also completely sequenced for the Vaucheria strains and Asterosiphon. The psb A‐ rbc L spacer was the most variable region that was sequenced, and only the 3′ end of the spacer could be aligned. Phylogenetic analyses (maximum parsimony, neighbor joining, and maximum likelihood) were conducted using the DNA sequence and the amino acid sequence for the rbc L gene, and a second analysis was conducted using a portion of the psb A‐ rbc L spacer + rbc L gene + RUBISCO spacer. All analyses showed that Vaucheria species formed monophyletic clades that corresponded with morphologically based subgeneric sections, including the section Racemosae. Species producing a gametophore (= fruiting branch, bearing both an antheridium and oogonium) formed a monophyletic clade in all analyses. The nongametophore species sometimes formed a monophyletic clade but other times formed a basal grade. Pair‐wise comparisons of nucleotides and amino acids showed that for some species, numerous nucleotide changes resulted in relatively few amino acid changes. Consequently, phylogenetic analysis of the amino acids produced numerous trees, which in a strict consensus tree resulted in numerous polychotomies. An original strain of V. terrestris that was deposited in two culture collections over 25 years ago had identical sequences, suggesting no rapid change was occurring in the sequenced regions. Two strains of V. prona , isolated from Europe and North America, had identical sequences. Other species, for which two or more strains were examined, had different sequences. These results suggest that cryptic species complexes exist within Vaucheria because the rbc L gene is a conservative gene that is identical in other protists.