According to the results of a genetic analysis of more than 3,000 dogs, wolves, and coyotes, a gene important for human hearing may determine whether a dog's ears will be floppy like a Basset Hound's or short like a Rottweiler's.
The study was presented in January at the conference on plant and animal genomes in San Diego, California. It showed that DNA variants near the MSRB3 gene are associated with ear length in dogs. The results were also published in Scientific Reports.
People have previously studied ear positioning, but no one has studied ear length in dogs. Ear length and shape in dogs vary greatly depending on the breed. Some of these differences have developed naturally: it is believed that short erect ears lose less heat than long floppy ones, and dogs from cold climate regions typically have smaller ears than those from warm regions.
But selection has also influenced the shape of dogs' ears. It is believed that the long ears of the Basset Hound help it better capture scents during hunting, while the erect ears of the German Shepherd may slightly enhance its hearing.
Tori Rudolph, a researcher at the Dog Genetics Laboratory at the University of Georgia in Athens, and her colleagues analyzed the genomes of thousands of dogs in search of sequence differences that correlate with ear length. Their search led them to a region of the genome near MSRB3, a gene that encodes an antioxidant protein associated with ear size in pigs, sheep, and goats. Some mutations in this gene are linked to hearing loss in humans, and previous studies have associated this gene with floppy ears in dogs.
According to Rudolph and her colleagues, the DNA variants they discovered may increase the activity of MSRB3, enhancing the rate of cell division in the ear.
The analysis focused on small changes in DNA consisting of a single letter, but some physical differences may be due to other types of genetic variations, such as large deletions or duplications in the genome.
After studying the variability of sequences in different dog breeds, Rudolph, inspired by her two Golden Retrievers, Erin and Brooks, now wants to see what can be learned by studying a single breed.
"Golden Retrievers have very different ear sizes and lengths," she says. "They would be the perfect subject for my next study."
Recently, it has been found that some dogs can remember the names of objects by eavesdropping on their owners' conversations.
