Mitogenomic characterisation of non-native freshwater snails in Australia: Implications for biosecurity and trematode vector surveillance.
This genomic study enhances biosecurity preparedness by providing molecular tools for monitoring non-native snail species in Australia.
Where it sits
this study against the rest of the nad+ (nicotinamide adenine dinucleotide) corpusSummary and findings
This study characterized the complete mitochondrial genomes of four non-native freshwater snail taxa in Australia and one potential invader species. Using long-read sequencing, 15 complete mitogenomes were assembled and compared across three snail families. The findings provide molecular references for biosecurity and vector surveillance efforts.
Abstract
Freshwater snails play essential roles in the transmission of trematode parasites that affect humans, livestock and wildlife. Australia's freshwater ecosystems are increasingly influenced by non-native and potentially invasive snail species that may pose biosecurity challenges and alter parasite transmission dynamics. This study characterised the complete mitochondrial genomes for four non-native snail taxa established in Australia (<i>Pseudosuccinea columella</i>, <i>Orientogalba viridis</i>, <i>Physa acuta</i> and <i>Planorbella</i> sp.) and for <i>Galba truncatula</i>, a high-priority exotic species considered a potential invader. Using long-read sequencing and comparative analyses, 15 complete mitogenomes were assembled, annotated and compared across three families (Lymnaeidae, Physidae and Planorbidae). Genome sizes ranged from 13.7 to 14.3 kb and exhibited conserved gene organisation and marked A + T bias. Australian populations of <i>P. columella</i>, <i>O. viridis</i> and <i>Ph. acuta</i> showed very limited mitochondrial nucleotide variability, consistent with founder effects, demographic bottlenecks and self-fertilisation, in contrast to the marked divergence observed among lineages within <i>Galba</i> from European laboratory strains. Phylogenetic inference based on concatenated and single-gene (cytochrome <i>c</i> oxidase subunit 1, <i>cox</i>1) datasets confirmed well-resolved family-level relationships and revealed cryptic diversity within <i>Galba</i>. The mitogenomes defined here provide molecular references for future taxonomic studies, diagnostic assay development and environmental (e)DNA monitoring of freshwater snails. These genomic resources establish a basis for biosecurity preparedness and vector surveillance in Australia and contribute to a broader One Health approach by supporting early detection, accurate identification and risk assessment of trematode-transmitting snails in freshwater ecosystems.
Background
The study addresses the biosecurity and ecological implications of non-native freshwater snails in Australia, which are vectors for trematode parasites affecting humans and animals. Understanding the genetic makeup of these snails is crucial for monitoring and managing potential invasions and parasite transmission. Prior research has focused on the ecological roles of these snails, but comprehensive genomic data were lacking.
Methods
The study utilized long-read sequencing to assemble and annotate 15 complete mitochondrial genomes from four non-native snail taxa and one potential invader species in Australia. The snails belong to three families: Lymnaeidae, Physidae, and Planorbidae. Phylogenetic analyses were conducted using concatenated and single-gene datasets to explore genetic relationships and diversity.
Results
The primary finding was that genome sizes ranged from 13.7 to 14.3 kb, with conserved gene organization and A + T bias. Australian populations of certain snail species exhibited limited mitochondrial nucleotide variability, suggesting founder effects and demographic bottlenecks. In contrast, significant genetic divergence was observed among European Galba lineages. Phylogenetic analyses confirmed family-level relationships and identified cryptic diversity within Galba.
Interpretation
The study provides essential genomic resources for future taxonomic and diagnostic studies, contributing to biosecurity and vector surveillance in Australia. While the genetic findings are significant, their direct ecological or health implications remain to be explored. The limited genetic variability in Australian populations could impact their adaptability and ecological roles, but further studies are needed to assess these effects.
Key findings
- Genome sizes ranged from 13.7 to 14.3 kb.
- Australian populations showed limited mitochondrial nucleotide variability.
- Marked divergence observed among European Galba lineages.
- Phylogenetic inference confirmed well-resolved family-level relationships.
- Cryptic diversity revealed within Galba.
Limitations
- Genomic characterization only, no ecological impact assessment.
- Limited to Australian populations, with some European comparisons.
- Focus on mitochondrial genomes, not nuclear DNA.