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MORPHOLOGICAL AND MOLECULAR PHYLOGENIES OF HALIMEDA (CHLOROPHYTA, BRYOPSIDALES) IDENTIFY THREE EVOLUTIONARY LINEAGES
Author(s) -
Hillis Llewellya W.,
Engman James A.,
Kooistra Wiebe H. C. F.
Publication year - 1998
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.1529-8817.1998.340669.x
Subject(s) - biology , phylogenetic tree , synapomorphy , evolutionary biology , phylogenetics , genus , holdfast , molecular clock , halimeda , zoology , clade , ecology , coral reef , genetics , gene
Halimeda Lamouroux 1812 colonizes most benthic euphotic habitats of tropical reefs worldwide; yet, despite its ecological importance and long fossil record, little is known about the evolutionary history of this complex of 33 described species. This report is the first within a developing, comprehensive study of the genus, of which the goals were to determine the major lineages within the genus, compare them with current taxonomic circumscriptions, and begin to evaluate the phylogenetic information that can be gleaned from morphology. We present the first formal phylogenetic analysis based on 23 morphological characters and the last 723 nucleotides of the 3′ end of the rDNA 18S gene including an insertion of approximately 102 bp. Fourteen samples from 10 species representing four sections were included. Independent analysis of both data sets yielded congruent topologies, with the molecular data set offering more resolution. Thirteen of the 23 morphological characters were phylogenetically informative. Holdfast type, cortical branching pattern, and nodal configuration were the key synapomorphies. The 18S rDNA sequence including secondary structural analysis revealed 139 variable positions, of which 58 (42%) were informative. Thirty‐two of the informative positions (55%) were found in the insertion. Three principal lineages were identified corresponding to sections Opuntia and Micronesicae, Rhipsalis, and Halimeda. In the molecular analyses, Flabellia petiolata (Turra) Nizamuddin was included as outgroup but did not resolve relationships among the lineages. Our results provide the basis for detailed phylogenetic and biogeographic studies within specific sections of the genus and for exploration of the evolutionary diversification of large complexes such as H. opuntia and H. discoidea.