Affiliations 

  • 1 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya 16310 Bachok, Kelantan, Malaysia; China-ASEAN College of Marine Sciences, Xiamen University Malaysia 43900 Sepang, Selangor, Malaysia. Electronic address: suhnih.tan@xmu.edu.my
  • 2 Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8572 Japan
  • 3 Faculty of Resource Science and Technology, Universiti Malaysia Sarawak 94300 Kota Samarahan, Sarawak, Malaysia
  • 4 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak 94300 Kota Samarahan, Sarawak, Malaysia
  • 5 First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
  • 6 Natural History Museum of Denmark, University of Copenhagen, 1353 Copenhagen K, Denmark
  • 7 Department of Bioinformatics, Biocenter, University of Würzburg, Am Hubland 97074 Würzburg, Germany
  • 8 Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China
  • 9 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya 16310 Bachok, Kelantan, Malaysia
  • 10 Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya 16310 Bachok, Kelantan, Malaysia. Electronic address: cpleaw@um.edu.my
Harmful Algae, 2025 Jan;141:102769.
PMID: 39645396 DOI: 10.1016/j.hal.2024.102769

Abstract

The benthic pennate diatom Nitzschia navis-varingica, known for producing domoic acid (DA) and its isomers, is widely distributed in the Western Pacific (WP) region. To investigate the genetic differentiation and gene flow patterns among the populations in the WP, the genetic diversity of 354 strains of N. navis-varingica was analysed using two nuclear-encoded rDNA loci: the large subunit rDNA (LSU rDNA) and the internal transcribed spacer 2 (ITS2). Frustule morphology of each strain was examined by TEM. The LSU rDNA phylogeny revealed a monophyletic lineage encompassing all strains, with sequence divergences of <0.9 %. Phylogenetic and population genetic analyses of ITS2 identified eight distinct clades (designated as Groups A to H) with moderate to high genetic heterogeneity (0.5-19.7 %). The low genetic differentiations between the geographically separated populations (pairwise FST of <0.03) suggested high gene flow and lack of spatial genetic structuring. Molecular clock analysis of the ITS2 phylogeny traced the evolutionary history of N. navis-varingica to the Eocene Epoch, and the split between clades likely occurred from the mid-Miocene to Pleistocene Epochs (10.8-1.2 Ma). The population dispersal in the WP were likely influenced by historical events like the Quarternary glacial cycles during the period, contributing to its homogenous distributions in the region.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.