Genomic basis for skin phenotype and cold adaptation in the extinct Steller's sea cow

Steller’s sea cow, an extinct sirenian and one of the largest Quaternary
mammals, was described by Georg Steller in 1741 and eradicated by humans
within 27 years. Here, we complement Steller’s descriptions with
paleogenomic data from 12 individuals. We identified convergent evolution
between Steller’s sea cow and cetaceans but not extant sirenians,
suggesting a role of several genes in adaptation to cold environments.
Among these are inactivations of lipoxygenase genes, which in humans and
mouse models cause ichthyosis – a skin disease characterized by a thick,
hyperkeratotic epidermis that recapitulates Steller’s sea cows’ reportedly
bark-like skin. Finally, we found that Steller’s sea cows’ abundance was
continuously declining for tens of thousands of years prior to their
description, implying that environmental changes also contributed to their
extinction.