help raise pups ultimately shorten the sex lives of the male pups when they grow up, according to findings published this week in the journal Proceedings of the Royal Society B. Conversely, she-wolves with nannies enjoy a longer reproductive life.

“The negative impact to males was certainly not what we expected to find,” said Amanda Sparkman, an evolutionary biologist at Trent University in Ontario who led the study.

The work could help conservationists maintain reintroduced populations of Canis rufus rufus, as the red wolf is known, which first became extinct in the wild about 30 years ago. But Sparkman says it could add another tool to chip away at the genetics behind mammals that contribute to raising juveniles that aren’t their own.

“In the context of cooperative breeding, there’s some fascinating evolutionary biology going on there,” Sparkman said. “More work could help us understand the key problem of why these wolves are cooperative breeders, along with about 3 percent of mammals and 3 percent of birds.”

Red wolf packs roamed most of eastern North America 1 to 2 million years ago, when modern genetics tell us they split off from their coyote relatives. Yet fueled by fear of the man-eating wolves of yore and the threat to livestock, colonists hunted and poisoned the carnivore to extinction in the wild by 1980.

“[Conservationists] took the last few individuals into a captive breeding program, however, and it has been one of the most successful to date,” Sparkman said. As a result of those efforts, wolves are back from the dead, though listed as critically endangered under the Endangered Species Act.

Sparkman went a step farther than conservationists and leaned on 23 years of red wolf data, including a full pedigree of 463 radio-collared canines, to tease out the findings.

“This is really exemplary data, a kind people just don’t have on reproduction and survival of a large carnivore,” she said.

Wild red wolves live anywhere from 4 to 7 years, with old-timers lasting as long as 13 years. Most pups stick around their pack for about 1 or 2 years, sometimes nannying their younger siblings each spring before heading out on their own to find a mate and start their own pack.

Using pedigrees and other data from captured and radio-collared wolves, Sparkman discovered nannied pups survived more often and stuck around their packs about a year longer than non-nannied wolves. What’s more, nannied females grew up smaller but enjoyed reproductive lifespans nearly double that of non-nannied she-wolves. Males cared for by pack members outside of their parents grew bigger than other pups, yet their sex lives were almost halved.

“This may tie in to other studies about metabolism,” Sparkman said, noting faster aging could be a cost for being bigger. “So, smaller females may live and breed longer because their metabolic cost is less.”

In the end, Sparkman suspects some evolutionary twist is at work in the wolves rather than learned behavior, seeing as the creatures were wiped out, reintroduced and still practice cooperative breeding.

“I’d say there is definitely a genetic basis overall, but what is actually producing it?” she said. “That’s the real question.”

Images: U.S. Fish and Wildlife Service Red Wolf Recovery Project/Greg Koch

See Also:

• A Theory of Evolution for Evolution
• 8 Most Overlooked Endangered Species Candidates
• Fossil Dog May Be Ancestor of Africa’s “painted” Canids
• Why Can’t We Be Friends? Top 10 Interspecies BFF Videos
• Darwin’s Wolf Mystery Solved
• Fossil Jaw Could Be From World’s Oldest Known Dog

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Authors: Dave Mosher

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