Disease Made Today's Wolf Fur Colors Possible, Study Shows

According to research, the wolves' present-day fur colors have emerged because of a disease, not because the canines, whose habitats span North America and Eurasia, are always gray.

Disease and Dark Fur Colors

According to research, the wolves' present-day fur colors have emerged because of a disease, not because the canines, whose habitats span North America and Eurasia, are always gray. For a long time, the phenomenon went unrecognized, but now researchers have found the cause. Disease, one of the main forces behind natural selection, appears to have played an important part in this matter.

According to research conducted by an international team headed by Sarah Cubaynes, an ecologist from the University of Montpellier in France, the frequently lethal canine distemper virus is the catalyst that increases the population of black-coated wolves (Canis lupus).

Tim Coulson, a biologist from the University of Oxford, said that black wolves are absent or extremely rare in the majority of the world, but they can be found in North America in some places and not at all.

He added that Because of extraordinary data gathered by co-authors who work in Yellowstone, Coulson has an explanation for the phenomenon that has long baffled scientists. It is based on wolf surveys conducted across North America and modeling.

Evolution Through Disease

Particularly when it comes to disease, the pressure of evolution can have some odd effects. Depending on which genes confer resistance to that disease, some people may have a higher chance of surviving. The genetic makeup of a population can start changing over time as a result of the survivors giving birth to offspring with these same genetic variations.

However, the genetic arrangements that confer resistance frequently serve more than one purpose. We are still experiencing the effects of the Black Plague centuries later because genetic variations that conferred resistance against it also increased susceptibility to autoimmune diseases like rheumatoid arthritis.

Read also: Germany Orders Shoot-to-Kill for Hybrid Wolf-Dog Pups to Protect Local Wolf Populations 

Gene CPD103 and the Canine Distemper Virus

The development of a black coat in wolves was caused by a CPD103 mutation that first appeared in dogs. But unlike human red hair, the black coat gene only needs one copy to produce a black coat.

Given that the DNA region where CPD103 is located is also involved in the encoding of a protein that protects against lung infections such as canine distemper, scientists hypothesized that the canine distemper virus may be a factor in the prevalence of black-coated wolves across North America.

This would imply that wolves with black coats would reproduce and pass on their CPD103 variant to their cubs if they were more likely to survive the disease. Researchers looked at 12 wolf populations in North America to determine whether there was a strong correlation between black-coated wolves and the presence of canine distemper antibodies, a marker for having experienced and survived the virus.

Only 5% of the black wolves had the black-coat CPD103 variant in two copies. This suggests that wolves choose partners of the opposite color to increase their chances of having offspring that survive canine distemper, the University of Oxford reports. However, it only functions in areas where canine distemper outbreaks have occurred.

Science Behind Color

The study not only provides an intriguing explanation for why black wolves are more common in some regions, but it also provides a tool for examining past canine distemper outbreaks and disease resistance.

The group observes that a wide range of species is probably affected by their findings. Color variation can be linked to disease resistance in a wide variety of insects, amphibians, mammals, reptiles, and birds; this coloration may serve as a signal to help animals select mates, which might give their offspring a survival advantage, Science Alert reports.

The research by Coulson and his colleagues has been recently published in the Journal Science.

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