Study finds tuna traits evolved slowly after asteroid ^{CEFR B2}

Researchers produced a time‑calibrated evolutionary tree for Scombridae by combining genetic data with fossil specimens and tissue samples from several institutions, including the Yale Peabody Museum. Scombridae comprises tunas and mackerels and accounts for about half of living warm‑blooded, ray‑finned fish species. The team placed the family’s origin near the K‑Pg asteroid strike 66 million years ago, but found the later evolution of large size and endothermy was more complex.

The analysis shows that large body size and warm‑bloodedness evolved independently in separate Scombridae lineages rather than in a single, rapid burst after the extinction. Endothermy evolved three times in the family, with at least two of those events occurring 10 to 15 million years after the asteroid. The authors conclude that the body plans of these predators developed over tens of millions of years and that the K‑Pg extinction did not trigger the evolution of large, endothermic tunas and relatives, as lead author Chase Brownstein notes.

The findings have both scientific and conservation implications. Senior author Thomas Near says better understanding of tuna evolution can support conservation, and he highlights the sharp decline of Atlantic bluefin tuna in recent decades due to overfishing. Near also suggests that studying endothermy could inform basic knowledge of metabolism and thermoregulation, while adding there is no explicit connection to human disease at this time. The research was published in Proceedings of the Royal Society B and received support from several funds and the National Science Foundation.