Seadragon Genomes Reveal Secrets of Syngnathid Evolution
Our collaborative team has published the first high-quality genomes of leafy and weedy seadragons in PNAS, revealing the genomic innovations underlying the spectacular biology of syngnathid fishes.
Evolutionary Marvels
Syngnathid fishes (seahorses, pipefishes, and seadragons) exhibit some of nature’s most remarkable adaptations: - Male pregnancy - unique among vertebrates - Loss of pelvic fins and ribs - Elaborate leaf-like appendages in seadragons - Prehensile tails in seahorses - Absence of stomach and teeth
Key Genomic Discoveries
Our analysis revealed:
Transposable Element Expansion
- Seadragon genomes contain 20-25% transposable elements
- Higher than other teleost fish (typically 5-10%)
- May drive rapid morphological evolution
Gene Family Evolution
- Loss of genes for stomach development (consistent with anatomy)
- Expansion of immune gene families (possibly related to male pregnancy)
- Modified developmental gene regulation
Comparative Insights
Comparing seadragons with seahorses and pipefish revealed: - Convergent gene losses across lineages - Lineage-specific innovations for unique traits - Rapid evolution of reproductive genes
Team Effort
This project represents six years of collaboration involving: - Lead authors: Clayton Small, Hope Healey, Mark Currey - International partners: Australia, Germany, Sweden - Sequencing: PacBio long-reads plus Hi-C scaffolding - Computational: Custom annotation pipeline for non-model organisms
Conservation Implications
Both seadragon species are near-threatened. Our genomic resources will aid: - Population genetics for conservation management - Understanding adaptive potential - Identifying populations at risk - Informing protection strategies
Open Data
All data are publicly available: - Genome assemblies on NCBI - Annotation files on FigShare - Analysis code on GitHub - Protocols on protocols.io
Publication: Small CM, Healey HM, Currey MC, Beck EA, Catchen J, Lin ASP, Cresko WA, Bassham S (2022). Leafy and weedy seadragon genomes connect genic and repetitive DNA features to the extravagant biology of syngnathid fishes. PNAS 119(26):e2119602119.