Canis soupus: eastern wolf genetics and its implications for wolf recovery in the Northeast United States. (Canid Conservation).
AbstractEfforts to restore wolves to the northeastern United States have been confounded by a new taxonomic proposal: that the wolf historically inhabiting this region was not, as previously thought, a subspecies of gray wolf commonly called the eastern timber wolf (Canis lupus lycaon), but rather a separate species closely related to the red wolf (Canis rufus) of the southeast United States. This hypothesis raises numerous biological legal, policy, and management questions about potential wolf restoration. While restoring wolves could complete a broken food chain by providing a natural predator for moose in the northern forest ecosystem, the process of wolf restoration in the Northeast is in its infancy. Further studies must address biological, sociological and economic impact questions, as well as answer the basic question of what wolf originally inhabited the northeastern forests?
Introduction
Efforts to restore wolves to the northeastern United States have been confounded by a new taxonomic proposal: that the wolf historically inhabiting this region was not, as previously thought, a subspecies of gray wolf commonly called the eastern timber wolf (Canis lupus lycaon), but rather a separate species closely related to the red wolf (Canis rufus) of the southeast United States (Wilson et al. 2000). This hypothesis raises numerous legal, policy, and management questions about potential wolf restoration. In addition, wildlife managers now have a basic biological question to consider when debating the merits of wolf reintroduction to New England and upstate New York: what wolf should be restored?
Wolves were extirpated from the Northeast by the end of the nineteenth century (Fowler 1974). In 1974, a year after passage of the Endangered Species Act (ESA), the U.S. Fish and Wildlife Service (FWS) listed eastern timber wolves as endangered, except in Minnesota where a remnant population was listed as threatened. In 1978, the Service developed a recovery plan for the eastern timber wolf. At that time, scientists believed that the eastern timber wolf had historically ranged throughout the Northeast and west to the Great Lakes region. The recovery plan identified several areas in the Northeast as potential wolf habitat, including northwest Maine and the Adirondack Mountains of New York. These areas remained in the recovery plan when it was revised in 1992 but the Service did not actively pursue northeast wolf restoration.
A recent proposal by the Service to declare a Distinct Population Segment for wolves in the Northeast (Federal Register 2000) has triggered renewed interest in wolf recovery in this region. If enacted, this designation would separate the Northeast administratively under the ESA from wolf populations in the Great Lakes states and require the Service to develop a new recovery plan for New England and upstate New York. Recent studies indicate there are adequate habitat and prey to sustain a healthy wolf population in this region (Harrison and Chapin 1997; Mladenoff and Sickley 1998), and several surveys indicate strong public support for wolf restoration (Responsive Management 1996; Downs and Smith 1998). However, the unresolved issue of taxonomy, while certainly not the only impediment to northeast wolf restoration, is complicating the prospect.
Previous taxonomic classification
In this article, we use the term eastern wolf to refer to the wolf that, by Nowak's description (1995), currently resides in southeastern Canada and formerly inhabited the northeastern United States. We also use the term western gray wolf to refer to what Nowak (1995) describes as Canis lupus nubilus, the larger wolf that formerly inhabited much of the western United States and much of Canada. Goldman (1937) classified the eastern wolf as Canis lupus lycaon, a subspecies of gray wolf, and for years its historic range was thought to be the northeastern United States as far west as the Great Lake states and north into southern Ontario and Quebec (Goldman 1944; FWS 1992; Nowak 1995). The red wolf is classified as Canis rufus, a distinct species (Goldman 1937), and its historic range has long been considered to be the southeastern United States as far west as Texas and as far north as Pennsylvania (Nowak 1995). By these boundary definitions, the ranges of the red wolf and eastern wolf would have originally overlapped in the mid-Atlantic states (Nowak 1995), including Pennsylvania, West Virginia, and Virginia (see Figure 1).
[FIGURE 1 OMITTED]
Over the years, scientists noted similarities between the two canids based on morphology and skull measurements (Lawrence and Bossert 1975; Alexander 1983 ). The two animals are apparently so similar that one report in the literature 25 years ago refers to a red wolf in Algonquin Park, Ontario (P. Wilson, personal communication), even though scientists did not think they ranged that far north.
Recipe for canid soup
Scientists noted another trait common to both red wolves and eastern wolves--the tendency to hybridize with coyotes, Canis latrans (Wilson et al. 2000). Coyotes, historically absent from the east, reached Ontario in the early 1900s as habitat alteration and fragmentation favored their eastward expansion (Clarke 1970; Wayne and Lehman 1992; Roy et al. 1994). In the 1920s, coyotes moved east across southern Ontario and eastern Quebec and by the 1930s had reached New York and New England (Parker 1995). The southeastern United States similarly underwent landscape changes that enabled coyotes to expand to this region as gray and red wolves were extirpated in the last century (Jenks and Wayne 1992; Parker 1995).
As coyotes expanded eastward, they encountered dwindling populations of both eastern and red wolves. There has been much discussion in the literature about the propensity for and degree of interbreeding between red wolves and coyotes, both earlier this century and since their reintroduction in North Carolina (Wayne and Jenks 1991; Nowak 1992; Kelly et al. 1999 ). At present, the FWS is struggling to keep reintroduced red wolves from hybridizing with coyotes. If the current rate of interbreeding is not halted, red wolf genes will be completely diluted within a few generations in a process known as genetic swamping (Kelly et al. 1999).
Genetic testing of the relatively large coyotes from the Adirondack Park and central New York similarly indicates a history of interbreeding with wolves. The degree of wolf genetic material varies across these samples, with some being more "wolf-like" than others (Chambers 2000). Genetic testing on northern New England canids shows interbreeding as well, though more sampling is needed. In the Frontenac Axis region of Ontario, southeast of Algonquin Park, a similar, though slightly larger canid is commonly called the Tweed wolf, and is probably a hybrid containing more wolf genes than coyote genes (Edwins et al. 2000; P. Wilson personal communication). A coyote-wolf mix is commonly found west of Algonquin Park, whereas the park itself maintains the most wolf-like form of eastern wolf (Wilson et al. 2000).
The result of these genetic analyses is the discovery of a canid gradient in the northeastern United States and southeastern Canada, containing a mix of eastern wolf, western gray wolf and coyote genes. This phenomenon is often lightheartedly referred to as "canid soup." According to Wilson et al. (2000), in the northeastern United States, coyote genes dominate this mix. In southeastern Ontario, eastern wolf genes are more common, and in northeastern and northwestern Ontario an eastern wolf/western gray wolf animal may be predominant. The extent to which eastern wolves interbreed with western gray wolves is currently unknown. The regions in far northern Ontario are predicted to be predominantly western gray wolf, but at present the boundary between the eastern wolf and western gray wolf is not well established (P. Wilson, personal communication).
Genetic hypothesis
The tendency for eastern and red wolves to hybridize with coyotes is not observed in western gray wolves (Edwins et al. 2000; Wilson et al. 2000). Additionally, there are morphological characteristics shared by red and eastern wolves but not western gray wolves, such as the smaller size of wolves in the East (Goldman 1944). These commonalities led researchers to examine more closely the relationship between red wolves and eastern wolves. They hypothesized that red and eastern wolves were more closely related to each other than either was to western gray wolves (Wilson et al. 2000). In the past decade, researchers from the genetics labs at Trent and McMaster's universities in Ontario have conducted genetic analyses of canids from throughout the red and eastern wolf range, using various criteria to compare relatedness. Their data support the hypothesis that the red wolf and eastern wolf have a common North American origin separate from that of the western gray wolf. In fact, these researchers suggest that the red wolf and eastern wolf are actually the same species, and they propose changing the scientific name of both to Canis lycaon, with a common name of red wolf (Wilson et al. 2000). The recommended name is based on historical precedence in early wolf taxonomy (Brewster and Fritts 1995).
According to Wilson et al. (2000), North America was inhabited by a common canid ancestor one to two million years ago. At some point, some of these animals traveled to Eurasia over the Bering land bridge and evolved into the gray wolf. The remaining canids evolved wholly in North America. Between 150,000 and 300,000 years ago they diverged into the coyote, which adapted to preying on smaller mammals in the arid southwest, and the eastern/red wolf, which adapted to preying on white-tailed deer (Odocoileus virginianus) in eastern forests. Gray wolves returned to the North American continent approximately 300,000 years ago, adapting to preying on large ungulates throughout the western United States and Canada. According to this hypothesis, coyotes are more closely related to the eastern/red wolf than to the western gray wolf, hence the propensity for interbreeding (Wilson et al. 2000).
Discussion
If the issue of eastern canid taxonomy is the subject of debate for academicians, it is nothing less than confounding to the public, legislators and even wildlife managers, who want to make informed decisions about wolf restoration in the Northeast. The concept that the eastern wolf and red wolf are the same species complicates an already complex topic, presenting numerous questions to all those interested in examining the potential for wolf recovery in New England and New York. What canid originally occupied the Northeast and what canid is there now? What role is the present canid filling and what role would a restored, larger canid fill? What wolf population would scientists use as source animals, and would they displace or interbreed with the Northeast's resident coyotes?
Because of the tendency of the eastern wolf to hybridize with coyotes, it is a fair assumption that if it were reintroduced in the Northeast it would be vulnerable to interbreeding with eastern coyotes. Therefore, despite efforts to reintroduce a separate species in the Northeast, biologists might just be regenerating an animal that is already present in the form of a large, hybrid coyote. It is important to note, however, that the core population of eastern wolves within Algonquin Park is not readily hybridizing with coyotes, although the reason for this is unclear (Edwins et al. 2000). Habitat saturation by established wolf packs might be one explanation. Protected wolves that are able to maintain long-term territories are able to prevent the encroachment of coyotes into core wolf areas (J. Theberge, personal communication). Canadian wolf researcher John Theberge has documented short-term invasion by coyotes following the breakup of a resident wolf pack within Algonquin's core wolf zone (J. Theberge, personal communication). Understanding this relationship could prove useful in the Northeast to determine what conditions are necessary to discourage interbreeding.
From an ecological perspective, wildlife managers will have to determine what the most appropriate species of wolf is for the modern day moose-dominated North Woods. Should a species' historical presence be the determining factor, or should the most suitable candidate be selected to match the ecological conditions existing today or likely to exist in the future? If so, the wolves in the Laurentides area of Quebec might provide a better source population for the northeastern United States. The close proximity of the two regions might allow some genetic exchange. Preliminary testing indicates that genetically, the Laurentides animals may be a mix of gray and eastern wolf (P. Wilson, personal communication), a finding which is further supported by their large size of up to 100 pounds. The Laurentides wolves prey primarily on moose (Alces alces), a plentiful prey item in Maine. Most importantly perhaps, these animals may be less likely to hybridize with eastern coyotes than the Algonquin-type wolf, though this crucial relationship remains to be tested (P. Wilson, personal communication). In the world of survival of the fittest, it is unlikely that natural selection would favor a moose-eating canid that compromises its size by breeding with the much smaller eastern coyote.
This theorizing, however, begs the question: did this larger gray wolf ever exist in the Northeast? For now, scientists can only speculate, but it is generally accepted that the northeastern United States was primarily a moose-caribou ecosystem before European settlement (D. Harrison, personal communication). It is questionable whether the deer-adapted eastern wolf would have thrived in this environment, indicating that perhaps both canids--the larger gray wolf and the smaller eastern wolf--might have inhabited the northeast at various points (P. Wilson, personal communication). Given the radical changes that have occurred in the Northeast ecosystem since colonial times, and the lack of remaining physical evidence of the presence of wolves, it is difficult to determine which species may have been present.
Similarly, some scientists speculate that the eastern wolf did not historically occur north of the Canadian border (P. Wilson, personal communication). Southeastern Canada was home to moose, woodland caribou (Rangifer tarandus caribou) and elk (Cervus elaphus) and would have more likely contained the larger gray wolf. Overhunting and habitat alteration likely contributed to the decline of some of these species, including the wolf (Nelson 1997). As intensive logging encroached into southeastern Canada, white-tailed deer populations expanded northward from the United States, thriving in the second growth forests that resulted. Eastern wolf populations may have likewise moved north in an expansion similar to their primary prey species. Today, the range of the eastern wolf may extend as far west as Saskatchewan and include northwestern Ontario and Minnesota. These northern areas may contain both eastern wolves and western gray wolves, but more research is needed before this can be determined (Wilson et al. 2000).
The sociological implications of the new taxonomic proposal are as challenging as the biological. Wolf restoration is always politically divisive. Groups and individuals opposing wolf restoration have already latched onto the current debate, declaring that the role of the eastern wolf is filled by the large, resident eastern coyote, which many call the "brush wolf." If scientists determine that the Laurentides animal is the most suitable for Northeast reintroduction, but cannot definitively prove its earlier existence there, would the public accept a species whose original range may have stopped short of the proposed reintroduction area? These types of debates will most certainly slow the process of wolf restoration.
Conclusion
While the current genetics research is intriguing, and increasingly gaining the support of the scientific community (Kelly, personal communication), further research and discussion is essential before conclusions can be drawn. In the meantime, other biological factors are ripe for wolf restoration. The northern forests have made a remarkable recovery in the last fifty years and now comprise more than 26 million acres--ample habitat to support a population of wolves (Harrison and Chapin 1998; Mladenoff and Sickley 1998). With the expansion of moose and beaver (Castor canadensis) and the occurrence of white-tailed deer throughout the north woods, there is ample prey. Most scientists agree that there is an ecological role for a larger canid in the northeast's North Woods (Harrison quoted in Fascione and Kendrot, 2000). Even though coyotes occasionally form packs, they do not normally prey on moose. Restoring wolves could complete a broken food chain by providing a natural predator for moose in the northern forest ecosystem. Since the 1995 wolf reintroduction in the northern Rockies, the Greater Yellowstone ecosystem has undergone significant ecological changes as a result of the restoration of this top predator. Recent research in Yellowstone National Park suggests that the effect wolves have on their prey can benefit vegetative structure and overall species biodiversity (Ripple and Larsen, in press).
The process of wolf restoration in the Northeast is in its infancy, however, and further studies must address biological, sociological and economic impact questions (Fascione et al. 2000). While the proposed taxonomic revision highlights the need to identify the connections and potential interactions between eastern wolves, red wolves, gray wolves and eastern coyotes in the Northeast, a clearer picture of these complex relationships is not likely to simplify the management, policy, legal, and moral issues that follow. Although the questions raised by this taxonomic discussion are unique to the Northeast, controversy itself is nothing new to wolf restoration. Ultimately, genetics are just one more piece of information that wildlife managers, advocates, and the public will have to distill and blend with the ecological and sociological realities of not only today's environment, but tomorrow's as well.
Acknowledgments
The authors are very grateful to Paul Wilson, not only for reviewing this manuscript, but for always being willing to come out of the lab to explain this research. We would also like to thank Paul Nickerson, Michael Amaral, Bob Ferris and Martin Smith for their review and feedback.
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Nina Fascione Defenders of Wildlife, 1101 14th St. NW, Suite 1400, Washington DC 20005; [email protected] Lisa G. L. Osborn Defenders of Wildlife, P.O. Box 756, Shelburne, VT 05482; [email protected] Stephen R. Kendrot USDA/APHIS/Wildlife Services, P.O. Box 130, Hull Street Rd., Mosely, VA 23120; [email protected] Paul C. Paquet Faculty of Environmental Design, University of Calgary, Calgary, AB, Canada; [email protected]
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| Author: | Fascione, Nina; Osborn, Lisa G.L.; Kendrot, Stephen R.; Paquet, Paul C. |
|---|---|
| Publication: | Endangered Species Update |
| Date: | Jul 1, 2001 |
| Words: | 3761 |
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