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PHYLOGENY OF ZYGNEMOPHYCEAE BASED ON COX III GENE SEQUENCE DATA
Author(s) -
Hewitt D.,
Karol K. G.,
McCourt R. M.
Publication year - 2000
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.1529-8817.1999.00001-90.x
Subject(s) - biology , paraphyly , clade , monophyly , phylogenetics , phylogenetic tree , nuclear gene , gene , genome , evolutionary biology , genetics
Molecular phylogenetic analysis of the conjugating green algae (Class Zygnemophyceae) using nuclear (SSU rDNA) and chloroplast ( rbcL ) gene sequences has resolved hypotheses of relationship at the class, order, and family levels, but several key questions will require data from additional genes. Based on SSU and rbc L sequences, the Zygnemophyceae and Desmidiales are monophyletic, and families of placoderm desmids are distinct clades (Desmidiaceae, Peniaceae, Closteriaceae, and Gonatozygaceae). In contrast, the Zygnemataceae and Mesotaeniaceae are paraphyletic, although whether these two traditional families constitute a clade is uncertain. In addition, relationships of genera within families have proven resistant to resolution with these two oft‐used genes. We have sequenced the cox III gene from the mitochondrial genome to address some of these ambiguous portions of the phylogeny of conjugating green algae. The cox III gene is more variable than rbc L or SSU rDNA and offers greater resolving power for relationships of genera. We present preliminary analyses of coxIII sequences from each of the traditional families of Zygnemophyceae and contrast the resulting topologies with those derived from nuclear and chloroplast genes.