1. Historically, North America was home to at least two species of large canids. The gray wolf, Canis lupus, existed in forests throughout most of North America, where they preyed on large ungulates such as elk and moose. The much smaller coyote, C. latrans, was restricted to the plains and deserts of central and western North America, where they fed on much smaller prey. Coyotes and wolves are easily distinguished by morphology. Since 1900, wolves have been almost completely extirpated in the United States, though populations still exist in Canada. In response to declines in wolf populations, coyotes dramatically increased their range northward and eastward. Coyotes also took advantage of concomitant losses in habitat due to deforestation and agriculture that turned forested areas into a more open habitat.
In 2003, a research team (Wilson et al. 2003) announced the startling discovery that mitochondrial DNA (mtDNA) from two wolf skins collected in New York State and Maine in the late 1800’s did not match mitochondrial DNA of known gray wolves. Both of these animals had mtDNA more similar to that of coyotes than of gray wolves! The mtDNA of the New York wolf nested within coyotes; but the mtDNA of the Maine wolf was on a deep branch near the split of gray wolves and coyotes. Yet, the skins morphologically appeared like those of wolves, not coyotes.
Part I:What is your interpretation of the results above describing wolves in North America? Can you predict the likely evolutionary fate of hybrids and the parental species? How could you test your ideas?
Reference:Wilson, P.J., S. Grewal S., T. McFaIDen, R. C. Chambers, and B. N. White. 2003. Mitochondrial DNA extracted from eastern North American wolves killed in the 1800s is not of gray wolf origin. Canadian Journal of Zoology 81(5):936-940.
2. This is an extension of the North American canid discussion question. To review, North America was home to at least two species of large canid. The gray wolf, Canis lupus, existed in forests throughout most of North America, where they preyed on large ungulates such as elk and moose. The much smaller coyote, C. latrans, was restricted to the plains and deserts of central and western North America, where they fed on much smaller prey. Coyotes and wolves are easily distinguished by morphology. Since 1900, wolves have been almost completely extirpated in the United States, though populations still exist in Canada. In response to declines in wolf populations, coyotes dramatically increased their range northward and eastward. Coyotes also took advantage of concomitant losses in habitat due to deforestation and agriculture that turned forested areas into a more open habitat.
In 2003, a research team (Wilson et al. 2003) announced the startling discovery that mitochondrial DNA from two wolf skins collected in New York State and Maine in the late 1800’s did not match mitochondrial DNA of known gray wolves. Both of these animals had mtDNA more similar to that of coyotes than of gray wolves! The mtDNA of the New York wolf nested within coyotes; but the mtDNA of the Maine wolf was on a deep branch near the split of gray wolves and coyotes. Yet, the skins morphologically appeared like those of wolves, not coyotes.
Part II:Today, due to the scarcity of their own species and the arrival of coyotes, the few wolves left in eastern North America often hybridize with coyotes. As a result, many wolves in eastern North America carry a confusing mixture of wolf and coyote alleles. Similar patterns are seen in another unusual population, the highly endangered “red wolf” of the southeastern United States. Thus, there appears to be a large amount of hybridization occurring in the few surviving wolf populations of North America.
Questions:
1.In the United States, hybrids are not protected under the Endangered Species Act. In Ontario, hybrids are afforded the same protection status as their parent species. Which do you think is the better policy? Why?2.Before the genetic discoveries, conservation biologists had been pursuing plans to reintroduce the gray wolf to Maine. Do you think they should proceed with this course of action? Please explain.