It’s a brutal disease, Smith says, causing those infected to become lethargic, vomit and cough before moving onto the animal’s nervous system. © Gregory “Slobirdr” Smith / Flickr A Deadly VirusĬanine distemper is a highly contagious virus similar to measles that likely arrived in South America with conquistadores in the 1700s, according to a 2019 paper published in the journal Frontiers in Microbiology.įrom there, the disease spread throughout canines including foxes, raccoons, skunks, coyotes, wolves and even wild cats like lions and tigers.

A black wolf in Yellowstone’s Lamar Valley. Wolves with two black genes, conversely, are the least likely to survive for reasons that still puzzle researchers.īut if wolves with two gray genes are most likely to reproduce, why, in places like Yellowstone, are there about as many black wolves as gray wolves? Because of disease and mate choice, researchers found. Why is up to speculation, though after decades of studying wolves in the Yellowstone region, Smith hypothesizes it’s because gray wolves have a tendency to be more aggressive and thus more successful surviving wolf conflict, finding a mate, and producing pups. Researchers realized that gray wolves-those with two gray alleles-are more likely to successfully reproduce. For those who have one of each, the black allele is dominant and the wolf, as a result, is black.īlack wolves, logic would follow, should then be dominant across the landscape, since two of the three combinations of genes result in black wolves.īut, broadly speaking, most wolves outside of the more southern ranges of the Rockies are gray. That means they either have two black genes, also called alleles, two gray genes, or one of each. Wolves get two genes that dictate coat color, one from each parent. Those in the more southerly regions of the Rockies, around Banff, Jasper and Yellowstone national parks tend to be split about half and half.Įxplaining how coat colors come to be is similar to why some people have green eyes versus brown or blond versus brown hair, says Doug Smith, one of the paper’s co-authors and a recently retired senior biologist at Yellowstone. Wolves outside of the southern Rocky Mountains-those in the Great Lakes region and northern Rocky Mountains and Alaska-tend to be predominantly gray. Outside of the Arctic, gray wolves, despite their name, have two main coat colors: gray and black. © Loren Merrill/TNC Photo Contest 2021 The Color of a Coat A member of Yellowstone’s Wapiti Lake wolf pack howls at the edge of a sagebrush meadow. The research continues to show just how much each new variation, each new introduction, can create rippling effects in species for thousands of years. Why? Hitching a ride on the gene that codes for black coats is an increased immunity to respiratory viruses like distemper.Ī paper explaining the phenomenon was published in the journal Science in late 2022 with more than a dozen co-authors from universities across France, the U.K.

“We also found that adults that survived distemper are more likely to be black.” “We found that there are more black wolves where distemper outbreaks are more frequent,” says Ellen Brandell, one of the paper’s co-authors and a wildlife research scientist with Colorado Parks and Wildlife. Thousands of years later, conquistadors landing in South America brought measles, dogs and a virus that causes distemper.įast forward to today-but a blink in evolutionary time-and researchers realized those two events likely collided and resulted in more black-colored wolves in the southern Rocky Mountains and more gray-coated wolves everywhere else. Sometime in the last 10,000 years or so, as humans migrated across the Bering Strait to North America, they brought dogs with a gene that ultimately gave gray wolves black coats.

Black grey wolf