Wolves: DNA Pawprinting
1994 Woodrow Wilson Collection
Wolves are the most widely distributed terrestrial carnivore. Their range includes Mexico, the Holarctic, Europe, Asia, the Middle East, Canada, Minnesota, Michigan, Glacier National Park. In the very near future, wolves will be reintroduced into Yellowstone Park. In 1990, the Alaska wolf population was estimated to be between 5900 and 7200 animals. Minnesota is home to 1550 to 1750 wolves; Northern Wisconsin has about 31 wolves. Isle Royale National Park in Michigan has a current population of about 10 wolves. In Northern Montana near Glacier National Park, there are 40 to 50 animals. Occasionally, someone reports seeing a wolf in Yellowstone Park. These animals are believed to be just passing through.
Wolves are great wanderers and individual gray wolves have been known to travel several thousand kilometers. Populations of animals with high mobility often have high rates of gene flow. Mitochondrial DNA analysis is becoming widely used to study populations of many animal species including wolves. Several enzymes are used to cut wolf mtDNA including Hind lll, Eco RI, and Bam HI. Gray wolf mtDNA genotypes vary about .16% in North America. The variation in mtDNA sequence between wolves and coyotes is about 3.1%. Dog genotypes differ from gray wolves by only one or two restriction sites or by about .2%.
In the early 1990's, a hunter in the Bridger-Teton Wilderness just south of Yellowstone Park shot a large animal that appeared outwardly to be a wolf. Because wolves were exterminated in Yellowstone Park by the Government during the period of 1914 to 1926, many people were skeptical about the identity of the animal. Some biologists thought that it was a wolf-dog or a wolf-coyote hybrid. Others thought that it was an animal raised in captivity then released into Yellowstone, and still others thought that it was truly a wild wolf which are occasionally sighted in the Greater Yellowstone Ecosystem.
- Which of the possibilities listed above do you think would best explain the true identity of the mystery animal? Please state two reasons why you hold that opinion:
- Based on your knowledge of biology, how could you go about collecting evidence to support your opinion? List three ways:
Restriction-site analysis of mitochondrial DNA has been used extensively in studying populations of many species of animals in the wild. Gray wolves show DNA patterns that are different from domestic dogs and coyotes and wolf-hybrids. DNA is collected from the blood or organ tissues from the heart, liver, or kidney.
- How would you go about collecting DNA from wolves in order to conduct your experiment to "DNA pawprint" the mystery animal?
- How many animals would you take samples from?
- Do you suppose that this has already been done? What would you do to find out!!!
Examine the bands of DNA shown in the diagram below. Use a ruler if necessary to determine which bands match most closely.
- Based on your observation, what is the identity of the mystery animal?
- Biologists believe that they will soon be able to use mitochondrial DNA to determine the female parent (wolf, dog, or coyote) of a hybrid animal. Why would this be possible? (Hint: think back to what you already know about fertilization and development!!)
- What ethical issue(s) are raised by the killing of this animal in the first place? The hunter stated that he thought the wolf-like animal was a coyote when he shot it. Was it right for him to kill it? State three reasons that support your opinion:
- Wolves will soon be reintroduced into Yellowstone Park. What problems do you foresee them encountering when they run into the following animals:
- dogs or coyotes
- Do you favor the reintroduction of wolves into Yellowstone Park? Why or why not? Write a brief paragraph stating your position and include the following terms: population, ecosystem, predator, and tourism.
- Wayne et al., December 1992. "mtDNA Variability of Grey Wolves," Conservation Biology, Vol.6, No.4.
- Lehman et al., 1991. "Introgression of Coyote Mitochondrial DNA," Evolution, Vol 45, 104-119.
- Mark S. Boyce, 1992. "Wolf Recovery for Yellowstone National Park: A Simulation Model," Wildlife 2001: Populations, Elsevier Science Publishers.
- Victor Van Ballenberghe, 1992. "Conservation and Management of Gray Wolves in the USA: Status, Trends, and Future Directions," Wildlife 2001: Populations, Elsevier Science Publishers.
- Hall et al., "1991 Application of DNA profiling to the Management of Endangered Species," The Zoological Society of London, International Zoological Yearbook.