• Neha Jagadish

Fish on Land

Fish had the capability to adapt to life on land as studies show that they share parts that were only known to be in land animals. Three genetic studies show that the precursors of land animals, tetrapods, were equipped with genes that could have made air-breathing lungs, limbs and a nervous system similar to that of land animals.


Fossils were a significant factor in the discovery of fish similarity to land animals. Researchers were able to tell that 375 million years ago, lobe-finned fish moved to shallow water and five million years later, they went to land. The fish who could set foot on the terrain must have possessed physical traits. Scientists did not understand how they could have obtained these changes for a long time.


Three studies published in “Cell” examined genes in living fish to learn more about evolution. Studies of mutagenized zebrafish helped the research progress. The studies found that in their front fins, zebrafish mutants had two bones that were similar to forelimbs of terrestrial animals.

The mutated genes, vav2 and wasib, were the reason for these similarities. Both genes code for proteins that control regulatory molecules in the body. These regulatory molecules help with the development of forearm bones in mammals. Generally, in fish, proteins would stop these bones from forming, but in these mutations, created by using clustered regularly interspaced short palindromic repeats (CRISPER) technology, the pathway reactivated. Discovering the mutations is a gamechanger for limb development.

These findings mean that the same genetic pathways must have been present in fish ancestors. Bodily functions and bones that have only been known to be in land animals can also be found in fish. Through research, a theory was formed that three key steps are involved in the change from water to land. First, the ability to breathe air appeared in the common ancestor, then new genes let fish leave their habitats in the water. Finally, the common ancestor of land vertebrates gained other respiratory changes required to survive on land. Evolution used genes already present in fish to adapt them to the land, rather than creating completely different genetic structures. This study is an important step in fully understanding the evolution of the fish-tetrapod transition.

Resources

  1. Fish had the genes to adapt to life on land—while they were still swimming the seas. (2021, February 10). Science | AAAS. https://www.sciencemag.org/news/2021/02/fish-had-genes-adapt-life-land-while-they-were-still-swimming-seas

  2. Knight, S. (2021, February 23). Fish had the genes to adapt to life on land while they were still swimming the sea. Front Line Genomics. https://frontlinegenomics.com/fish-had-the-genes-to-adapt-to-life-on-land-while-they-were-still-swimming-the-sea/

  3. We’re more like primitive fishes than once believed, new research shows. (2021, February 5). ScienceDaily. https://www.sciencedaily.com/releases/2021/02/210205210627.htm

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