Saturday, January 17, 2015

Are wolves endangered with extinction in Alaska?

alaskan wolf
Wolves in the panhandle of southeast Alaska are currently being considered as an endangered species by the US Fish and Wildlife Service in response to a petition by environmental groups. These groups are proposing that the Alexander Archipelago wolf (Canis lupus ligoni) subspecies that inhabits the entire region and a distinct population segment of wolves on Prince of Wales Island are threatened or endangered with extinction.

Whether or not these wolves are endangered with extinction was beyond the scope of our study. However our research quantified the genetic variation of these wolves in southeast Alaska which can contribute to assessing their status as a subspecies.

Because the US Endangered Species Act (ESA) defines species as “species, subspecies, and distinct population segments”, these categories are all considered “species” for the ESA. Although this definition is not consistent with the scientific definition of species it has become the legal definition of species for the ESA.

Therefore we have two questions to consider:
  • Are the wolves in southeast Alaska a subspecies?
  • Are the wolves on Prince of Wales Island a distinct population segment?
The literature on subspecies and distinct population segment designation is vast, but it is important to understand that subspecies is a taxonomic category, and basically refers to a group of populations that share an independent evolutionary history.

Taxonomy is the science of biological classification and is based on evolutionary history and common ancestry (called phylogeny). Species, subspecies, and higher-level groups (e.g, a genus such as Canis) are classified based on common ancestry. For example, wolves and foxes share common ancestry and are classified in the same family (Canidae), while bobcats and lions are classified in a different family (Felidae) because they share a common ancestry that is different from foxes and wolves.
Wolf in southeast Alaska.  Photo credit: Kristian Larson, the Alaska Dept of Fish and Game. Image used with permission.
Wolf in southeast Alaska. Photo credit: Kristian Larson, the Alaska Dept of Fish and Game (Wildlife Conservation Division, Region I). Image used with permission.
Subspecies designations are often subjective because of uncertainty about the relationships among populations of the same species. This leads many scientists to reject or ignore the subspecies category, but because the ESA is the most powerful environmental law in the United States the analysis of subspecies is of great practical importance.

Our results and other research showed that the wolves in Southeast Alaska differed in allele frequencies compared to wolves in other regions. Allele frequencies reflect the distribution of genetic variation within and among populations. However, the wolves in southeast Alaska do not comprise a homogeneous population, and there is as much genetic variation among the Game Management Units (GMU) in southeast Alaska as there is between southeast Alaska and other areas.

Our research data showed that the wolves in southeast Alaska are not a homogeneous group, but consist of multiple populations with different histories of colonization, isolation, and interbreeding. The genetic data also showed that the wolves on Prince of Wales Island are not particularly differentiated compared to the overall differentiation in Southeast Alaska and do not support designation as a distinct population segment.

The overall pattern for wolves in southeast Alaska is not one of long term isolation and evolutionary independence and does not support a subspecies designation. Other authors, including biologists with the US Fish and Wildlife Service, also do not designate wolves in southeast Alaska as a subspecies and there is general recognition that North America wolf subspecies designations have been arbitrary and are not supported by genetic data.

There is growing recognition in the scientific community of unwarranted taxonomic inflation of wildlife species and subspecies designations to achieve conservation goals. Because the very nature of subspecies is vague, wildlife management and conservation should focus on populations, including wolf populations. This allows all of the same management actions as proposed for subspecies, but with increased scientific rigor.

Headline image credit: Alaskan wolf, by Douglas Brown. CC-BY-NC-SA-2.0 via Flickr.