DNA Res 2026 Jul 14; doi: 10.1093/dnares/dsag008.

The genome of a keystone predator: Adaptive innovations in Charonia tritonis drive specialized predation and coral reef resilience.

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The giant triton snail (Charonia tritonis) is an ecologically critical predator that controls coral reef ecosystems by preying on crown-of-thorns starfish (COTS). However, overharvesting has driven severe population declines, threatening reef health. Despite its importance, the genomic underpinnings of its unique adaptations-including toxin resistance, prey detection, and environmental resilience-remain poorly understood. Here, we present the first chromosome-level genome assembly of C. tritonis (3.8 Gb), the largest sequenced gastropod genome, which encapsulates the large repetitive sequences comprising 70.1% of the genome and fueling massive genomic expansion. Macrosynteny and molecular dating analysis confirm a Jurassic-era (∼190 Mya) whole-genome duplication (WGD) that facilitated adaptive innovation. Comparative analyses identified gene family expansions critical to C. tritonis' ecological dominance: 1) toxin resistance via immune/detoxification systems (e.g., galectins, Toll-like receptors, CYP450 enzymes); 2) Sensory specialization (e.g., rhodopsin expansions) enhancing prey detection in complex reef habitats; and 3) DNA repair pathways (RADX proteins) supporting longevity and UV resistance. Tissue-specific expression profiling confirmed tentacle-exclusive localization of sensory receptors, directly linking genomic adaptations to foraging behavior. This study provides foundational insights into the evolution of a keystone marine predator, offering actionable genetic targets for conservation strategies and illuminating mechanisms that shape predator-prey coevolution in coral reefs.

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