Finding the genes that help kingfishers dive without hurting their brains

If you've ever belly-flopped into a pool, then you know: water can be surprisingly hard if you hit it at the wrong angle. But many species of kingfishers dive headfirst into water to catch their fishy prey. In a new study in the journal Communications Biology, researchers compared the DNA of 30 different kingfisher species to zero in on the genes that might help explain the birds' diet and ability to dive without sustaining brain damage.

"For kingfishers to dive headfirst the way they do, they must have evolved other traits to keep them from hurting their brains," says Shannon Hackett, associate curator of birds at the Field Museum and the study's senior author.

For this study, the researchers examined the DNA of 30 species of kingfishers, both fish-eating and not. "To get all the kingfisher DNA, we used specimens in the Field Museum's collections," says Eliason, who works in the Field's Grainger Bioinformatics Center and Negaunee Integrative Research Center. "When our scientists do fieldwork, they take tissue samples from the bird specimens they collect, like pieces of muscle or liver. Those tissue samples are stored at the Field Museum, frozen in liquid nitrogen, to preserve the DNA."

The scientists found that the fish-eating birds had several modified genes associated with diet and brain structure. For instance, they found mutations in the birds' AGT gene, which has been associated with dietary flexibility in other species, and the MAPT gene, which codes for tau proteins that relate to feeding behavior.

Tau proteins help stabilize tiny structures inside the brain, but the accumulation of too many tau proteins can be a bad thing. In humans, traumatic brain injuries and Alzheimer's disease are associated with a buildup of tau.

Image source: Luca Casale, Wikimedia Commons, CC BY-SA 4.0