Small genome to fly

2007/03/12 Roa Zubia, Guillermo - Elhuyar Zientzia

• Eboluzioa
• Genetika

In general, the genome of birds is smaller than that of mammals and reptiles. It seems that this has to do with the ability to fly, but how? What is the cause and what is the consequence? Does flying make the genome smaller or do birds fly through its small genome? Some paleontologists have discovered that the right choice is the second, that is, that in evolution the genome was reduced before birds fly. To find out, they studied the fossils of the ancestors of the birds, dinosaurs, because in their bones you

can see that they had a small or large genome. The genome itself is not seen in fossils, but in the size of cells, and those of small genome develop small cells. In fact, in fossils they have seen that the ancestors of birds had small cells. Moreover, the cells were reduced at an evolutionary time, 60 million years before the appearance of birds. According to scientists, the repetitive parts of the genome disappeared in the ancestors of the birds, thereby reducing the

cells. The smaller the cells, the more surface they have compared to the inner volume. This has a great influence on cell membrane activity: molecules quickly enter and exit the cell, obtaining a fast metabolism. All this is evident in current birds, especially those that have not stopped flying. Ostriches, for example, have a larger genome than flying birds. It is clear that to fly you have to have a light genome.