HOWL Colorado

Detangling the subspecies controversy

[large thumbnail url=”detangling-the-subspecies-controversy” filename=”science” year=”2010″ month=”04″ day=”22″] [thumbnail icon url=”detangling-the-subspecies-controversy” filename=”science” year=”2010″ month=”04″ day=”22″] There is a great deal of confusion over the number of subspecies of the gray wolf, which lived where, which should live where and the differences between them.

Depending on who you talk to there are as many as 24 subspecies of gray wolf in North America, or as few as four.

Old science?

Over centuries past, biologists have designated many wolf populations as a subspecies of canis lupus (or gray wolf).

Try and keep up as we do a whirlwind tour of the various subspecies.

– alces (Kenai Peninsula wolf) – extinct
– arctos (Arctic Wolf)
– baileyi (Mexican gray wolf) – critically endangered
– beothucus (Newfoundland wolf) – extinct
– bernardi – extinct
– columbianus
– crassodon
– fuscus – extinct
– griseoalbus
– hudsonicus
– irremotus (Northern Rocky Mountain wolf) – thought to be extinct
– labradorius
– ligoni
– lycaon (Eastern wolf) – may be its own species
– mackenzii
– manningi
– mogollonensis – extinct
– monstrabilis – extinct
– nubilus (Great Plains wolf) – thought to be extinct until population found in north central United States
– occidentalis (Rocky Mountain or MacKenzie Valley wolf)
– orion
– pambasileus
– tundraru
– youngi (Southern Rocky Mountain wolf) – extinct

These 24 subspecies were officially accepted (and still are an acceptable way to classify wolf subspecies) in 1981 and were developed by E. Raymond Hall and K. R. Kelson in 1959. The distinctions between these subspecies are either geographical, morphological (anatomical), or some specific unique natural history.

One area of contention in recent history was during the wolf reintroduction into Yellowstone National Park.

The reintroduction was challenged on the basis that the Endangered Species Act did not allow for reintroduction of a species into a region which had an existing population from the same species. The wolf subspecies from the area of Montana, Idaho and Wyoming was canis lupus irremotus – a subspecies which was on the Endangered Species List before the main gray wolf species.

Legal challenges fell short of stopping the reintroduction when courts agreed that the US Fish and Wildlife Service had every reason to believe that irremotus was effectively extinct and that a single animal did not constitute a population.

What modern sciences says…

The last couple of decades have seen some biologists begin to scale back on the number of subspecies they recognize.

Prior to the official adoption of the 24 subspecies, Dr. L. David Mech observed that so many subspecies were unnecessary, and that many lacked the necessary differentiators to earn them a standalone subspecies designation.

There are a few reasons that wolf populations would be misclassified as distinct subspecies.

The population represented a sample size too small to effectively determine the differences necessary to accurately identify a new subspecies

Wolf migration and extensive range obscures possible distinct subspecies through significant interbreeding

Variation within the same subspecies can be quite significant in terms of size and color.

This new way of thinking about wolves was outlined in a tangible way at the 1992 North American Wolf Symposium when mammalogist and author Ronald Nowak presented findings based on analyzing wolf skulls identifying only five distinct subspecies. Nowak’s consolidated subspecies list is also officially accepted in addition to Hall’s earlier defined 24 subspecies list and both are widely accepted.

canis lupus arctos (arctic wolf)

canis lupus lycaon (eastern wolf) – which some believe is a species of it’s own – not just a subspecies.

canis lupus occidentalis

canis lupus baileyi (Mexican gray wolf)

canis lupus nubilus

There are also some biologists who believe that the domestic dog is close enough to their ancestors (able to interbreed with and produce fertile young for example) that they could be classified as a wolf subspecies (canis lupus familiaris).

Continuously contentious…

There are still claims that the reintroduced wolves which now make their home in Montana, Idaho and Wyoming are “Canadian” wolves and as such are bigger, and more aggressive than the “native” species (which at the time would have been the then extinct or near-extinct irremotus).

There are a few problems with this claim. Some have switched their selection of “native” species to be canis lupus nubilus – based on the fact that Nowak suggested that irremotus was a subset of nubilus.

The problem with this is, of course, that nubilus has a range which stretches through the western United States, up in to Canada and even up to Alaska.

This creates two problems.

First, and most obvious, of course is that canis lupus nubilus would also be a Canadian wolf – since wolves pay little attention to borders.

Second, with such a massive range, there is good reason to believe that canis lupus occidentalis (western Canada and Alaska) and canis lupus nubilus have regularly crossed paths and hunt similar prey.

The other major issue is that there has been a pretty significant sample size (about 20%) of the Idaho wolf population which has been weighed in the last 6 months thanks to the wolf hunt.

The average weight of the 188 wolves killed in the 2009 Idaho wolf hunt was less than 100lbs.

The claim that occidentalis is more aggressive is also pretty subjective and doesn’t seem to have much supporting evidence.

There is some truth in that occidentalis is a little larger on average than some other wolf subspecies. However, the evidence of the small size of the wolves in Idaho, it seems clear that wolves (regardless of subspecies) are similar to many other animals in that their size is predominantly determined by environment and availability of prey.

Is a gray wolf just a gray wolf?

After all of this confusion over subspecies, there are some who may just be feeling that a gray wolf is just a gray wolf and that the added complexities of the subspecies adds unnecessary smokescreen to an already controversial topic.

Perhaps there is some truth to that. But regardless of whether you believe there are two dozen subspecies, half a dozen subspecies or that the subspecies are somewhat irrelevant, it is clear that it is not a point around which anti-wolf camps can build a plausible argument.

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