Intraspecific genetic diversity with unrestricted gene flow in the domoic acid-producing diatom Nitzschia navis-varingica (Bacillariophyceae) from the Western Pacific
Document Type
Article
Publication Date
1-1-2025
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.
Keywords
Amnesic shellfish poisoning, Diatom, Frustule, Harmful algal bloom, Second internal transcribed spacer, Transmission electron microscopy
Divisions
ocean
Funders
Ministry of Education, Malaysia,Higher Center of Excellence Fund [HICoE IOES-2023B] (LRGS/1/2020/UMT/01/1/3)
Publication Title
Harmful Algae
Volume
141
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS