The wolves that live on Lake Superior's Isle Royale are completely isolated from all other wolves...or so we thought. One immigrant wolf injected some much-needed fresh genes into the mix, and we know because of the poop he left behind.
We briefly touched on this story in our recent epic poop treatise, but this is a topic that really deserves some further examination, and not just for its poop-related aspects.
The Isle Royale wolf population was founded in the late 1940s, and it's been under close scientific observation ever since. Researchers had assumed that the wolves were completely cut off from their relatives on the mainland, but in 1997 one wolf crossed over to the island using an ice bridge, and his arrival may go a long way to keep the population genetically viable.
Nicknamed "The Old Gray Guy" because of his distinctive light gray coat, the immigrant wolf was larger than most of the native wolves, which allowed him to become alpha male of the Middle Pack, one of the three packs on Isle Royale that existed back in the late nineties. Researchers at Michigan Tech were able to track the Old Gray Guy using his poop, which contained some of his DNA. They discovered he possessed several crucially different genes that the native wolves did not, strongly suggesting he came from a distinct population.
The Old Gray Guy proved a very successful breeder, first mating with one of the native females from 1998 and 2000 and then with his own daughter until his death in 2006. His daughter then mated with one of the sons she produced with her father until her own death in 2010. I think we can safely say that wolf mating habits are somewhat different from our own and leave it at that, although good luck untangling the branches of that family tree.
Anyway, the Old Gray Guy ultimately had 34 children and 45 grandchildren, and that second figure is still on the rise. 56% of all wolf genes on Isle Royale can now be traced back to him, and his arrival created a temporary drop in inbreeding, although it quickly rose again (indeed, it appears he had more than a little to do with that rise).
What excites researchers about the Old Gray Guy is that he may have performed genetic rescue, which involves the sudden influx of new genes into an otherwise stale population. Isolated populations risk losing genetic diversity, which in turn makes them far more vulnerable to being totally wiped out by disease. In general, a population without genetic diversity is doomed, and it's only a matter of time before they meet their final end. It's rare to actually observe genetic rescue in nature, partly because immigrations like that of the Old Gray Guy are quite rare and partly because so few populations are under careful observation like the Isle Royale wolves.
Sadly, the genetic rescue may have come too late for the Isle Royale wolves. While there were once three packs, now there's only one pack of just sixteen wolves, and only two adult females have survived. If they can't raise more female pups, their population will likely die off. The current population decline isn't due to their stale genetics but rather a dwindling food supply, as Isle Royale's moose population has also dropped considerably in recent years. Still, the moose population is on the rise, so there's some hope that the wolf pack will survive...and at least part of the credit has to go to the Old Gray Guy's rather unique libido.