Shell-bound archives: uncovering nematode encapsulations in the Galapagos’ largest radiation
Abstract How macroevolution interacts with ecological networks remains a major question in eco-evolutionary science. We investigate this interplay in the Naesiotus snail radiation of the Galápagos Islands, which encapsulates parasitic nematodes within the shell—a recently discovered gastropod defense. Using a natural history collection, we examined dry shells from 47 species across 12 islands, quantified encapsulations, and sequenced nematode DNA to reconstruct a host-parasite network. Encapsulations were widespread and revealed high nematode diversity, including in snail hosts presumed extinct. Nematode diversity was shaped by habitat, while encapsulation load was better explained by host species identity, suggesting species-specific defenses. Neither trait showed phylogenetic signal, and shell brightness was unrelated to nematode interactions. Similarly, host diversification rate did not predict network position, suggesting that macroevolution may leave a weak or obscured imprint on this host-parasite network. This snail-nematode system in islands readily enables integration of ecological networks, phylogeny, functional traits, and biogeography.
Authors
- Robbie G. Rae (ORCID: https://orcid.org/0000-0001-5843-4029)
- Alexandre Fuster‐Calvo (ORCID: https://orcid.org/0000-0002-6416-5731)
- Gustavo Burin (ORCID: https://orcid.org/0000-0001-7851-0666)
- John Gilbert Phillips (ORCID: https://orcid.org/0000-0003-3974-4309)
- Dominique Gravel (ORCID: https://orcid.org/0000-0002-4498-7076)
- François Massol (ORCID: https://orcid.org/0000-0002-4098-955X)
- Ian M. Oiler (ORCID: https://orcid.org/0000-0001-7185-6285)
- A. Andrew M. MacDonald (ORCID: https://orcid.org/0000-0003-1162-169X)
Institutions
- Midwestern University (US)
- Centre National de la Recherche Scientifique (FR)
- Université de Sherbrooke (CA)
- University of Idaho (US)
- Durham University (GB)
- Université Paris-Est Créteil (FR)
- Université Paris Cité (FR)
- Sorbonne Université (FR)
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (FR)
- Institut d'écologie et des sciences de l'environnement de Paris (FR)
- Institut de Recherche pour le Développement (FR)
- Liverpool John Moores University (GB)
- University of Gothenburg (SE)
Publication Details
- Journal
- The American Naturalist
- Published
- 2026-11-09
- DOI
- https://doi.org/10.1086/744771
- Citations
- 1
- Primary Topic
- Parasite Biology and Host Interactions
- Type
- article
- Field-Weighted Citation Impact
- 4.78
Funders
- Natural Sciences and Engineering Research Council of Canada
- National Institute of General Medical Sciences