Biology subjects

Watervoort, N. F.

Publications and source records attributed to Watervoort, N. F..

3 recordsLinked to original sources

bioRxiv2026

Hybridization between toxic bloom-forming algae of the Prymnesium parvum sensu lato species complex

The potential for hybridization to act as a driver of genetic diversity and adaptation in harmful algal bloom-forming species has received scarce attention, despite growing recognition of its occurrence in diverse protist and algal lineages. Prymnesium parvum s.l. (Haptophyta), is a cryptic species complex whose members form ecosystem-disruptive toxic algal blooms around the world. A prior genome analysis showed that UTEX2797, a widely used laboratory strain, originated via hybridization between clade A1 and clade A2 of this species complex. To assess the extent of A1xA2 hybridization in P. parvum s.l., we screened the genomes of 28 strains and identified 16 additional A1xA2 hybrid strains isolated from inland Texas or the eastern United States between 2001 and 2020. Chloroplast haplotypes indicated that hybridization between A1 and A2 may have occurred multiple times, and hybrids with different chloroplast haplotypes have been co-isolated from blooms in Texas in 2013 and 2020. Additionally, strain NIES1812 from Okinawa, Japan was sufficiently divergent from A1 and A2 to warrant designation as a separate clade, which we name A3. These results provide evidence for a facultative sexual life cycle in P. parvum s.l. and expand our understanding of the extensive cryptic genetic diversity present in the species complex. The frequent isolation of hybrid strains from North American blooms suggests that hybridization is common and represents a significant source of adaptive potential in these economically and ecologically damaging organisms.

evolutionary biology↗

bioRxiv2026

Letter to the Editor regarding "Long-read genome sequencing provides novel insights into the harmful algal bloom species Prymnesium parvum" by Jian et al. (2024)

Jian et al. (2024) describe de novo genome assemblies for two strains of Prymnesium parvum (sensu lato, s.l.), a cryptic species complex of toxic, unicellular algae responsible for harmful algal blooms around the world. Here, we present evidence that the labels for UTEX 2797 and CCMP 3037 were inadvertently swapped by Jian et al. (2024). This resulted in sequence data labeled "UTEX 2797" but derived from strain CCMP 3037, and vice versa. Strain misidentification is a major risk with cryptic species like P. parvum s.l., and our reanalysis of the data in Jian et al. (2024) underscores the urgent need for clade-specific markers to ensure accurate and efficient strain identification.

genomics↗

bioRxiv2022

Extreme genome diversity and cryptic speciation in a harmful algal bloom forming eukaryote

Harmful algal blooms (HABs) of the toxic haptophyte Prymnesium parvum are a recurrent problem in many inland and estuarine waters around the world. Strains of P. parvum vary in the toxins they produce and in other physiological traits associated with HABs, but the genetic basis for this variation is unknown. To investigate genome diversity in this morphospecies, we generated genome assemblies for fifteen phylogenetically and geographically diverse strains of P. parvum including Hi-C guided, near-chromosome level assemblies for two strains. Comparative analysis revealed considerable DNA content variation between strains, ranging from 115 Mbp to 845 Mbp. Strains included haploids, diploids, and polyploids, but not all differences in DNA content were due to variation in genome copy number. Haploid genome size between strains of different chemotypes differed by as much as 243 Mbp. Syntenic and phylogenetic analyses indicate that UTEX 2797, a common laboratory strain from Texas, is a hybrid that retains two phylogenetically distinct haplotypes. Investigation of gene families variably present across strains identified several functional categories associated with metabolism, including candidates for the biosynthesis of toxic metabolites, as well as genome size variation, including recent proliferations of transposable elements. Together, our results indicate that P. parvum is comprised of multiple cryptic species. These genomes provide a robust phylogenetic and genomic framework for investigations into the eco-physiological consequences of the intra- and inter-specific genetic variation present in P. parvum and demonstrate the need for similar resources for other HAB-forming morphospecies. SIGNIFICANCE STATEMENTHarmful algal blooms (HABs) are a global concern. Efforts to understand the genetic basis of traits associated with the success of HAB-forming species are limited by a dearth of genomic resources. In this paper we present genomes for fifteen strains of Prymnesium parvum, a toxic alga that causes ecosystem and societally disruptive HABs around the world. We uncover an unprecedented amount of sequence-level, gene family, and genome architecture evolution in P. parvum and provide evidence for both cryptic speciation and hybridization. These results illustrate how both inter- and intraspecific genetic variation can be dramatically underestimated in a protist morphospecies. More work is needed to understand the eco-physiological consequences of hidden genetic diversity in P. parvum and HAB-forming species more generally.

evolutionary biology↗