According to 2017 data, there are more than 300 breeds of domestic rabbits in the world. The most unusual breed can rightfully be called the Alfora jumpers (sauteur d’Alfort), whose representatives at first glance seem to be ordinary, but during the run, they behave extremely strangely. They walk as usual, but they raise their hind legs high up and run only on their front legs if they need to run. Real acrobats! Scientists already knew that rabbits are forced to do this because, while running, their hind legs cannot move properly and almost drag behind the body. To prevent this from happening, the animals raise their hind legs and quickly move the front ones. The unusual behavior of rabbits is associated with a mutation that arose when the breed was bred by crossing. Scientists recently learned more about this genetic error.
What is the spinal cord for?
Animals need to have good coordination of movements. Thus, predators are more likely to catch prey, and weak animals are more likely to escape from enemies. The spinal cord, which is located inside the spine, is largely responsible for movement. The neurons inside the spinal cord control the rhythm of movement, muscle activity, and so on. Equally important, the spinal cord also coordinates the movement of the left and right limbs. The animal’s gait depends on this coordination: some species move on two limbs, while others – on four. Some animals alternate between the right and left limbs, while others synchronize them. For example, the hind legs of rabbits move synchronously during jumping.
The most unusual rabbits
The Alfa jumpers mentioned at the beginning of the article with coordination of movements were not lucky. At high speed, their hind legs cannot sync, so they literally drag behind their body. Therefore, while running, they raise their defective hind limbs upward and run using only their front legs. But this is not the only problem with Alfa jumpers. Researchers have long noticed that baby rabbits of this breed are often born blind.
Recently, scientists from Portugal and Sweden decided to figure out what all these ailments of rabbits are connected with. They conducted several genetic experiments and found that a mutation had occurred during the creation of the Alfa jumpers breed. It is observed in one single gene that leads to abnormal development of the spinal cord in animals. This gene is known as RORB, and its job is to instruct mammalian cells to produce specific proteins. The mutation led to the fact that a deficiency of substances caused a decrease in the number of neurons in the spinal cord.
In further work, scientists discovered that in other breeds of rabbits, protein deficiency in the spinal cord is not observed. They drew attention to a pattern: if there is no RORB gene mutation, rabbits can run and jump, and if something is wrong with the gene, rabbits run on their front legs. Based on this, the authors of the scientific work concluded that the RORB gene might be responsible for the ability to jump in other animal species. For example, this method of movement is preferred by kangaroos, antelopes, and so on.
According to Swedish geneticist Leif Andersson, many other genes also influence the way animals to move. However, a mutation in the RORB gene is exceptional when a change in one gene affects animals’ gait in such a radical way. There is no information on whether the mutation prevents rabbits from leading an able lifestyle. But if you think about it, not being able to use all of their legs diminishes their chances of surviving in the wild. Also, using only the front legs, they obviously get tired very quickly. And this, by the way, can affect the duration of their lives.