Evolutionary biologists have discovered unexpected relatives among different species of animals

Evolution is one of the main mysteries of the Earth. Since the days of Darwin, scientists have been struggling to resolve it, trying to determine how living things on the planet evolved, how they are related to each other and at what point completely different species of animals appeared from one branch. Recently, evolutionary biologists compiled a phylogenetic tree of the jaw vertebrates, the basis of which was the largest and most informative molecular phylogenetic data set ever analyzed by scientists. This construction sheds light on some secrets of evolution.

So different relatives

Jaw vertebrates are fish, amphibians, mammals (including humans), snakes, turtles, lizards, crocodiles and birds. There are thousands of species of these creatures, and they are all very different from each other, showing huge differences in species richness, life history, behavior and many other aspects of their biology. However, they all have a spine and jaw, which is where their name came from.

Since its origin, about 470 million years ago, the jaw vertebrates have been very divided: they include more than 68,000 described species, not counting extinct. Some of them developed abilities that allowed them to leave the water and conquer the earth on all continents during the Devonian period. They even learned to fly more than once.

The evolution of the jaw vertebrates is part of the history of human development. Therefore, an understanding of the evolutionary relationship between the jaw vertebrates remains one of the main unresolved mysteries in biology. For example, in some species, even after separation, similar evolutionary mechanisms appeared (the ability to fly in birds and bats, echolocation in the same mice and whales, and so on).

Molecular archeology

The latest study reconstructs a new phylogenetic tree of the jaw vertebrates, using a total of 7,189 genes from 100 species, each of which has a million nucleotides. This can be called "molecular archeology": based on the traces left by evolution in our DNA, the events that happened millions of years ago are restored.

The results reveal several “kinship” relationships between different types of maxillary vertebrates, which for decades have remained unproven. For example, double-breathing fish turned out to be the closest living relatives of terrestrial vertebrates.

It also revealed the close relationship of turtles with crocodiles and birds (archosaurs), as well as the special relations between groups of amphibians (salamanders, frogs and legless amphibians).

Some results make us reconsider previous hypotheses. For example, it was previously believed that the two main groups of birds and mammals separated after the extinction of dinosaurs about 67 million years ago. A new study shows that both groups are actually much older.

Scientists are confident that in the future this method can also be used to restore evolutionary relations between other mysterious groups of organisms, the secrets of which are still awaiting clues.