Subterranean Fishes of the World

6247

2023

Nature

450-453

619

Two colleagues have been exploring a 170-kilometre-long network of caves in Santander, a region of rivers, jungles and mountains in the eastern cordillera that had been severely affected by conflict. The caves formed over the past six million years and consist of a series of dead-end tunnels, separate from each other. Fish swam into them at different moments in history and were unable to leave, and so the system is like a set of test tubes, says Torres. In the tunnels, scientists discovered a new species of cave-dwelling catfish, Trichomycterus rosablanca, one of a group of related fishes that live in caves and surface streams. The fishes have differing degrees of adaptation to caves — for example, some have diminished eyes and others have lost them altogether. By sequencing the DNA of several individuals, the researchers demonstrated that the fish entered the tunnels at different times and, although separated from each other, acquired similar adaptations — a phenomenon known as convergent evolution. Since moving to an underground life, some species might also have developed enhanced sensory systems that enable them to operate in the darkness. “They have developed that over and over in this system in a short period of time,” says Torres.

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Flórez, J.S., Cadena, C.D., Donascimiento, C. and Torres, M. (2021)
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