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Living fossil: for 250 million years, sturgeon has hardly changed in appearance

Living fossil: for 250 million years, sturgeon has hardly changed in appearance

Charles Darwin was right. He once said that sturgeon is a living fossil. This is a very ancient type of fish. And modern scientists were able to prove that the evolution of the sturgeon almost did not affect. Specialists from the University of Würzburg sequenced the genome of sturgeon. They found that during the entire period of evolutionary development, sturgeons and their closest relatives - sterlets, have not changed much in appearance.

With the support of colleagues from France and Russia, the researchers successfully determined the sequence of the sterlet genome. The results showed that the genetic material of sturgeon and sturgeon has changed little since the time of the dinosaurs. Professor Manfred Schartl believes that the genomes of sturgeon are an important part of the big puzzle.

If you solve it, modern science will get important data about how vertebrates on our planet occurred, and how they evolved. Sturgeon is one of the oldest organisms on Earth. Sturgeon became the ancestor of almost 30 thousand species of bony fish that live in the vast oceans to this day. Researchers believe that more than 96 percent of all fish and animals could have had sturgeon among their distant ancestors. For some reason, the evolutionary development of this species of fish has stopped.

This phenomenon could have occurred approximately 345 million years ago. Since then, the appearance of the sturgeon has not changed much. The genetic background of this species has not changed much. Geneticists carefully studied the proteins of modern sturgeon and found out that they were encoded by sterlet genes. In laboratory experiments, they learned that the evolution of the protein was very slow.

The same rate of evolutionary development was observed in ancient shark species. The sterlet genome includes 120 chromosomes, 47.5 thousand genes, and 1.8 billion base pairs. The main genome has a repeat genome that is 180 million years old. It has the form of a set of chromosomes that science calls a tetraploidy. Gene duplication is not unexpected — such processes influence the evolution of the vertebrate genome. Some species go through this process 3-4 times during their evolution.

Scientists were surprised by the fact that in the history of sturgeon genome duplication occurred in the very distant past. Deep changes in the genome may have occurred over the long course of species' existence because, in tetraploid organisms, gene segments are often lost, silenced, or acquire a new function over time.

The genomic state of sturgeon is considered a subject of scientific controversy. Scientists have an opinion that sturgeon refers to a species that first duplicated its genome to become a tetraploid, and then reduced the content of the gene as it developed.