From Ed Yong at The Atlantic:
This jumping gene seems to have entered the cow genome from the unlikeliest of sources: snakes and lizards.
Retrotransposons typically jump around within a single genome, but sometimes they can travel further afield. Through means that scientists still don’t fully understand, they can leave the DNA of one species and enter that of another. And so it is with BovB. No one knows the animal in which it originated. But from that mystery source, it has jumped into the DNA of snakes and cows, elephants and butterflies, ants and rhinos.
No one knows how BovB travels between species, but Ivancevic and Adelson suspect that it might spread via blood-sucking parasites. They have found strong similarities between the BovB versions in leeches and zebrafish, bedbugs and snakes, ticks and lizards. By biting different hosts, parasites might help jumping genes to vault over the species barrier.
“It’s mind-boggling to think about how just a few [jumps] have fundamentally altered the course of our evolution,” says Chuong. Evolutionary biologists like to wonder what would happen if we replayed the tape of life—if we went back to some earlier point in history and let evolution run its course again. Would history repeat itself? Chuong thinks not. These jumps are so unpredictable, but so potentially important when they happen, that it’s hard to imagine the events unfolding twice. More.
If jumping genes can be this prevalent, evolution is about to become way more complex than the storied Tree of Life hammered into kids at school.
See also: No coherent “narrative” for transposable elements (jumping genes)?
Jumping genes make the tree of life a bush
Life continues to ignore what evolution experts say