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Phylogeny and species delineation in the marine diatom Pseudo‐nitzschia (Bacillariophyta) using cox1 , LSU , and ITS 2 rRNA genes: A perspective in character evolution
Author(s) -
Lim Hong Chang,
Tan Suh Nih,
Teng Sing Tung,
Lundholm Nina,
Orive Emma,
David Helena,
QuijanoScheggia Sonia,
Leong Sandric Chee Yew,
Wolf Matthias,
Bates Stephen S.,
Lim Po Teen,
Leaw Chui Pin
Publication year - 2018
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 - 10.1111/jpy.12620
Subject(s) - biology , phylogenetic tree , phylogenetics , clade , diatom , evolutionary biology , internal transcribed spacer , taxon , gene , botany , genetics
Analyses of the mitochondrial cox1 , the nuclear‐encoded large subunit ( LSU ), and the internal transcribed spacer 2 ( ITS 2) RNA coding region of Pseudo‐nitzschia revealed that the P. pseudodelicatissima complex can be phylogenetically grouped into three distinct clades (Groups I–III), while the P. delicatissima complex forms another distinct clade (Group IV) in both the LSU and ITS 2 phylogenetic trees. It was elucidated that comprehensive taxon sampling (sampling of sequences), selection of appropriate target genes and outgroup, and alignment strategies influenced the phylogenetic accuracy. Based on the genetic divergence, ITS 2 resulted in the most resolved trees, followed by cox1 and LSU . The morphological characters available for Pseudo‐nitzschia , although limited in number, were overall in agreement with the phylogenies when mapped onto the ITS 2 tree. Information on the presence/absence of a central nodule, number of rows of poroids in each stria, and of sectors dividing the poroids mapped onto the ITS 2 tree revealed the evolution of the recently diverged species. The morphologically based species complexes showed evolutionary relevance in agreement with molecular phylogeny inferred from ITS 2 sequence–structure data. The data set of the hypervariable region of ITS 2 improved the phylogenetic inference compared to the cox1 and LSU data sets. The taxonomic status of P. cuspidata and P. pseudodelicatissima requires further elucidation.