For more than a century, the evolutionary focus has been on the mechanism of species formation, based on dividing one line into two or more.And, as American ornithologists have shown, this can occur very often and without anthropogenic impact. Previously, it was believed that it is the reduction of habitats due to active economic activity that pushes animals from different lines to interbreed with each other.
After studying and comparing the sequences of nuclear and mitochondrial DNA of various representatives of the species of ordinary ravens (Corvus corax) from different habitats in the US and Mexico, the geneticists found out that the modern species of ordinary ravens formed from two separate lines that had spread about 1.5 million years ago. Mitochondrial DNA was obtained from 441 birds. In some cases, the samples were difficult, so pieces of cloth were taken from the museum exhibits. Part of the samples were obtained with the help of missile networks, which scientists fished crows to take their blood for analysis and release. But most of the DNA was obtained from carcasses of dead birds collected during a special expedition, the participants of which overcame 4,500 kilometers. For comparison, DNA samples of another species of this genus, the celandine crows (Corvus cryptoleucus), were also used.
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