Scientists have sequenced the genomes of "living fossils" of The Australian lungfish, or revealed clues to the evolution of life on land

According to New Atlas, genome sequencing can allow scientists to understand a lot of information about a species, and now scientists have completed the genome sequencing of one of the world's strangest and most interesting animals, the Australian lungfish. Considered a "living fossil", the Australian lungfish shows that it has the largest genome of any animal ever sequenced.

The Australian lungfish is one of the six lungfish species in the world and it is a peculiar creature. As the name suggests, it has a swim bladder (lung) on its back that allows it to breathe air, and because of the well-developed flesh of its pectoral and pelvic fins, it can "walk" on the riverbed like a salamander.

Combining these two characteristics, the Australian lungfish likes to crawl out of its home in rivers and freshwater pools and venture to dry land. It's not really an amphibian, but it's known it can leave the water for a few days — as long as its skin isn't too dry.

This is one of the most important steps in the history of evolution. During the Devonian period, about 420 million years ago, when the first animals crawled from the ocean onto dry land, the Australian lungfish was one of the closest closest relatives of these pioneer marine life, and because it remained largely unchanged over the course of more than 100 million years of evolution, its genome may have retained an understanding of that critical period.

So scientists in Europe began sequencing this complete genome. Scientists have sequenced many animals, plants, and microbes of interest, including humans, mice, worms, mosquitoes, Tasmanian tigers, sharks, apples, tomatoes, wheat, barley, and the Black Death.

The genome of the Australian lungfish was the largest ever sequenced animal, containing about 43 billion DNA base pairs. That's 14 times more than the human genome and a lot more than the 32 billion DNA base pairs of the previous record holder, the West-West salamander.

The team found that the staggering scale was largely due to repetition. About 90% of lungfish genomes are made up of repetitive sequences that vary in their position in the genome. In this regard, the team said that lungfish are actually closer to land vertebrates than other fish. With the full sequencing of the genome, the researchers were able to confirm that lungfish are the closest living fish relatives of tetrapods, which are absolutely huge groups of terrestrial animals, including amphibians, reptiles, birds, mammals, etc.

The scientists found that the genes that control the embryonic development of lungfish are the same as those in humans, suggesting that the evolution of the two species can be traced back to the same origin. The skeletal development of their fins is also controlled by the same genes as our hands. The team also found some genomic preadaptives for terrestrial life. The genome of lungfish has expanded in areas related to air respiration, limb development, reproduction, and the ability to smell. In conclusion, sequencing the Australian lungfish genome will help improve our understanding of one of the most important transitions in evolutionary history.

The study was published in the journal Nature.