Eyeless cavefish experienced independent instances of vision loss throughout over 11 million years of evolution.
In a groundbreaking study published in the journal Molecular Biology and Evolution, researchers have delved into the origins and evolution of blind, colorless cave fishes found in the eastern and southern states of the USA. The co-lead author of the study is Chase Brownstein, a student in Yale's Graduate School of Arts and Sciences, with Thomas Near, professor of ecology and evolutionary biology at Yale, serving as the senior author.
The study focused on Amblyopsidae, a family of cavefish that dwells in the fresh waters of the eastern and southern regions of the US, most notably the Mammoth Cave National Park in Kentucky. This family of cavefish has adapted to their subterranean environment, exhibiting elongated bodies, flattened skulls, and either reduced or completely lost pelvic fins.
The researchers examined the DNA of all known amblyopsid cavefish species, paying close attention to 88 genes related to vision. Their findings suggest that the cavefish genomes contain mutations similar to those that cause ocular diseases in humans. This discovery could potentially inform human health through translational medicine.
The study reveals that convergent evolution occurred in different species of cavefish, resulting in similar genetic solutions to survive in similar conditions. Interestingly, the researchers found that the evolution of these traits in cavefish is a striking example of convergent evolution in action.
One of the challenges faced in the study was dating the ancient subterranean ecosystems of eastern North America using traditional geochronological cave-dating techniques. However, the researchers were able to estimate the age of some caves based on when the mutations for blindness started to be advantageous for the fish. The minimum age of some caves is estimated to be over 11 million years based on the cavefish lineages.
It's worth noting that the study did not focus on cavefish species outside of the Amblyopsidae family. Similarly, it did not investigate the possibility of alien visitation.
The new study adds to our understanding of the evolution of these unique creatures, shedding light on their adaptation to life in the dark and providing valuable insights into the process of convergent evolution. With further research, these findings could lead to advancements in human health and our understanding of genetic diseases.
