Why Some Rabbits Walk On Their Front Feet With Their Back Legs In The Air?

Some rabbits can’t hop, and a single gene is the reason why. Mᴜᴛᴀᴛɪᴏɴs in this gene cause ᴅᴇfᴇᴄᴛs in the rabbits’ spinal cords, which mean they can’t coordinate their limbs well enough to perform a hop.

One ᴅᴇfᴇᴄᴛive gene might turn some bunnies’ hops into handstands, a new study suggests.

To move quickly, a breed of domesticated rabbit called sauteur d’Alfort sends its back legs sky high and walks on its front paws. That strange gait may be the result of a gene tied to limb movement, researchers report March 25 in PLOS Gᴇɴᴇᴛɪᴄs.

Sauteur d’Alfort rabbits aren’t the only animal to adopt an odd scamper if there’s a ᴍᴜᴛᴀᴛɪᴏɴ to this gene, known as RORB. Mice with a ᴍᴜᴛᴀᴛɪᴏɴ to the gene also do handstands if they start to run, says Stephanie Koch, a neuroscientist at University College London who was not involved with the rabbit work. And even while walking, the mice hike their back legs up to waddle forward, almost like a duck.

“I spent four years looking at these mice doing little handstands, and now I get to see a rabbit do the same handstand,” says Koch, who led a 2017 study published in Neuron that explored the mechanism behind the “duck gait” in mice. “It’s amazing.”

Understanding why the rabbits move in such a strange way could help researchers learn more about how the spinal cord works. The study is “contributing to our basic knowledge about a very important function in humans and all animals — how we are able to move,” says Leif Andersson, a molecular ɢᴇɴᴇᴛɪᴄist at Uppsala University in Sweden.

The team selectively bred sauteur d’Alfort rabbits and identified a region of their genome that differed from that of other rabbits. This region contained 21 protein-coding genes. The researchers then sequenced those genes and compared them with their counterparts in other types of rabbit.

They soon homed in on a ᴍᴜᴛᴀᴛɪᴏɴ in a gene called RORB. “This was the only ᴍᴜᴛᴀᴛɪᴏɴ that stood out as really sᴛʀɪᴋing,” says Andersson.

RORB is crucial for the formation of spinal cord neurons that link the left and right sides of the body, which are essential for coordinating limb movements. The team found that these body-crossing neurons didn’t form properly in newborn sauteur d’Alfort rabbits.

Many other genes surely play a role in locomotion and gait, and their effects will often be subtle, says Andersson. RORB is a rare case where a ᴍᴜᴛᴀᴛɪᴏɴ in a single gene produces a dramatic effect, revealing part of the underlying system.


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