Terrestrial birth and body size tune UCP1 functionality in seals

Michael J. Gaudry, Jane Khudyakov, Laura Pirard, Cathy Debier, Daniel Crocker, Paul G. Crichton, Martin Jastroch

Research output: Contribution to journalArticlepeer-review


The molecular evolution of the mammalian heater protein UCP1 is a powerful biomarker to understand thermoregulatory strategies during species radiation into extreme climates, such as aquatic life with high thermal conductivity. While fully aquatic mammals lost UCP1, most semiaquatic seals display intact UCP1 genes, apart from large elephant seals. Here, we show that UCP1 thermogenic activity of the small-bodied harbor seal is equally potent compared to terrestrial orthologs, emphasizing its importance for neonatal survival on land. In contrast, elephant seal UCP1 does not display thermogenic activity, not even when translating a repaired or a recently highlighted truncated version. Thus, the thermogenic benefits for neonatal survival during terrestrial birth in semiaquatic pinnipeds maintained evolutionary selection pressure on UCP1 function and were only outweighed by extreme body sizes among elephant seals, fully eliminating UCP1-dependent thermogenesis.

Original languageEnglish
Article numbermsae075
JournalMolecular Biology and Evolution
Issue number4
Early online date12 Apr 2024
Publication statusPublished - Apr 2024


  • brown adipose tissue
  • nonshivering thermogenesis
  • pinniped
  • pseudogene
  • UCP1

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