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Eight Diving Waterfowl Shared Genomic Signatures Linked to Underwater Foraging

Male red-breasted merganser swimming on open water
Research · Genetics & genomics

A comparative study of 25 waterfowl genomes found widespread evolutionary signals associated with diving-based foraging. The eight diving species designated as the focal diving lineages were common goldeneye (Bucephala clangula), long-tailed duck (Clangula hyemalis), surf scoter (Melanitta perspicillata), red-breasted merganser (Mergus serrator), African pygmy goose (Nettapus auritus), common eider (Somateria mollissima), black-headed duck (Heteronetta atricapilla) and ruddy duck (Oxyura jamaicensis).

The study, first published on 20 April 2026, compared diving species with non-diving relatives within Anseriformes. Because diving species occurred on several separate branches of the family tree, the researchers could look for evolutionary changes that appeared repeatedly in lineages that had independently adopted underwater foraging.

Selection signals involved several physiological systems

Genes showing signals of positive selection were especially common in functions related to metabolic and endocrine regulation, ion and solute transport, neural signalling, immune responses and cardiovascular regulation. Positive selection means that patterns of evolutionary DNA change are consistent with some gene variants having been favoured because they improved survival or reproduction. The authors interpret the repeated signals in diving lineages as molecular changes consistent with the demands of underwater foraging, including reduced oxygen availability and rising water pressure with depth.

The analyses also identified shared amino-acid substitutions across the diving lineages in genes including PKD1, PLB1 and GPR34. An amino-acid substitution changes one of the building blocks in a protein; finding the same change in separate diving lineages is a form of molecular convergence. PKD1 is involved in sensing mechanical forces and pressure, PLB1 in membrane and lipid processes, and GPR34 in immune regulation. Structural modelling suggested that some of the substitutions could alter how the proteins work, but this has not yet been tested experimentally.

Diving evolved in several parts of the waterfowl family tree

The eight diving species were distributed across multiple branches of the phylogenetic tree rather than forming a single diving lineage. The researchers therefore used non-diving relatives within the same order as comparisons when looking for repeated evolutionary patterns associated with underwater feeding.

The authors caution against treating the signals as proof of causation

The researchers stress that positive-selection signals do not by themselves prove that particular genes cause diving behaviour. Some patterns could instead reflect related traits such as cold tolerance, aquatic habitat use or aquatic foraging, and apparent convergence can also be influenced by shared ancestry. They also note that the predicted effects of amino-acid substitutions require experimental validation and that some diving lineages remain underrepresented in available genomic data.

The study provides a broad genomic comparison of diving and non-diving waterfowl within the same bird order. By finding repeated evolutionary signals across independently distributed diving lineages, it identifies candidate biological systems for future work on how species such as red-breasted merganser, common goldeneye and common eider cope with the energetic and physiological demands of feeding underwater.

Sources and image credit

  1. Xia, T., Zhang, L., Li, Y., Li, S., Gao, X., Zhou, S., Ding, J., Sun, G., Wang, X., Yang, X., Wu, X., & Zhang, H. (2026). Comparative genomics reveals genetic adaptations to diving-associated foraging in Anseriformes. Ecology and Evolution, 16(4), e73551. https://doi.org/10.1002/ece3.73551Primary open-access peer-reviewed study first published 20 April 2026. It compared 25 Anseriformes genomes obtained from NCBI, including eight diving species, and identified 13,873 orthogroups and 7,991 entirely single-copy orthogroups. Positive-selection signals and repeated amino-acid substitutions across diving lineages involved several physiological systems; the authors explicitly caution that these signals do not establish causation.

Image: Charles Homler / Wikimedia Commons — male red-breasted merganser (Mergus serrator) at Barnegat Inlet, New Jersey, USA, 1 March 2025. Illustrative photograph of one of the diving species in the genomic study; not a study animal. · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Genetics & genomics

SPECIES IN THIS STORY

Species in this story

Common Goldeneye Bucephala clangula Explore species Red-breasted Merganser Mergus serrator Explore species Common Eider Somateria mollissima Explore species

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