Species of canine
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The wolf (Canis lupus; pl.: wolves), also known as the grey wolf or gray wolf, is a canine native to Eurasia and North America. More than thirty subspecies of "Canis lupus" have been recognized, including the dog and dingo, though grey wolves, as popularly understood, only comprise naturally-occurring wild subspecies. The wolf is the largest wild extant member of the family Canidae, and is further distinguished from other "Canis" species by its less pointed ears and muzzle, as well as a shorter torso and a longer tail. The wolf is nonetheless related closely enough to smaller "Canis" species, such as the coyote and the golden jackal, to produce fertile hybrids with them. The wolf's fur is usually mottled white, brown, grey, and black, although subspecies in the arctic region may be nearly all white.
Of all members of the genus "Canis", the wolf is most specialized for cooperative game hunting as demonstrated by its physical adaptations to tackling large prey, its more social nature, and its highly advanced expressive behaviour, including individual or group howling. It travels in nuclear families consisting of a mated pair accompanied by their offspring. Offspring may leave to form their own packs on the onset of sexual maturity and in response to competition for food within the pack. Wolves are also territorial, and fights over territory are among the principal causes of mortality. The wolf is mainly a carnivore and feeds on large wild hooved mammals as well as smaller animals, livestock, carrion, and garbage. Single wolves or mated pairs typically have higher success rates in hunting than do large packs. Pathogens and parasites, notably the rabies virus, may infect wolves.
The global wild wolf population was estimated to be 300,000 in 2003 and is considered to be of Least Concern by the International Union for Conservation of Nature (IUCN). Wolves have a long history of interactions with humans, having been despised and hunted in most pastoral communities because of their attacks on livestock, while conversely being respected in some agrarian and hunter-gatherer societies. Although the fear of wolves exists in many human societies, the majority of recorded attacks on people have been attributed to animals suffering from rabies. Wolf attacks on humans are rare because wolves are relatively few, live away from people, and have developed a fear of humans because of their experiences with hunters, farmers, ranchers, and shepherds.
Etymology.
The English "wolf" stems from the Old English , which is itself thought to be derived from the Proto-Germanic . The Proto-Indo-European root *"wĺ̥kʷos" may also be the source of the Latin word for the animal "lupus" (*"lúkʷos"). The name "grey wolf" refers to the greyish colour of the species.
Since pre-Christian times, Germanic peoples such as the Anglo-Saxons took on "wulf" as a prefix or suffix in their names. Examples include Wulfhere ("Wolf Army"), Cynewulf ("Royal Wolf"), Cēnwulf ("Bold Wolf"), Wulfheard ("Wolf-hard"), Earnwulf ("Eagle Wolf"), Wulfstān ("Wolf Stone") Æðelwulf ("Noble Wolf"), Wolfhroc ("Wolf-Frock"), Wolfhetan ("Wolf Hide"), Scrutolf ("Garb Wolf"), Wolfgang ("Wolf Gait") and Wolfdregil ("Wolf Runner").
Taxonomy.
In 1758, the Swedish botanist and zoologist Carl Linnaeus published in his "Systema Naturae" the binomial nomenclature. "Canis" is the Latin word meaning "dog", and under this genus he listed the doglike carnivores including domestic dogs, wolves, and jackals. He classified the domestic dog as "Canis familiaris", and the wolf as "Canis lupus". Linnaeus considered the dog to be a separate species from the wolf because of its "cauda recurvata" (upturning tail) which is not found in any other canid.
Subspecies.
In the third edition of "Mammal Species of the World" published in 2005, the mammalogist W. Christopher Wozencraft listed under "C. lupus" 36 wild subspecies, and proposed two additional subspecies: "familiaris" (Linnaeus, 1758) and "dingo" (Meyer, 1793). Wozencraft included "hallstromi"—the New Guinea singing dog—as a taxonomic synonym for the dingo. Wozencraft referred to a 1999 mitochondrial DNA (mtDNA) study as one of the guides in forming his decision, and listed the 38 subspecies of "C. lupus" under the biological common name of "wolf", the nominate subspecies being the Eurasian wolf ("C. l. lupus") based on the type specimen that Linnaeus studied in Sweden. Studies using paleogenomic techniques reveal that the modern wolf and the dog are sister taxa, as modern wolves are not closely related to the population of wolves that was first domesticated. In 2019, a workshop hosted by the IUCN/Species Survival Commission's Canid Specialist Group considered the New Guinea singing dog and the dingo to be feral "Canis familiaris", and therefore should not be assessed for the IUCN Red List.
Evolution.
The phylogenetic descent of the extant wolf "C. lupus" from the earlier "C. mosbachensis" (which in turn descended from "C. etruscus") is widely accepted. Among the oldest fossils of the modern grey wolf is from Ponte Galeria in Italy, dating to 406,500 ± 2,400 years ago. Remains from Cripple Creek Sump in Alaska may be considerably older, around 1 million years old, though differentiating between the remains of modern wolves and "C. mosbachensis" is difficult and ambiguous, with some authors choosing to include C. "mosbachensis" (which first appeared around 1.4 million years ago) as an early subspecies of "C. lupus."
Considerable morphological diversity existed among wolves by the Late Pleistocene. Many Late Pleistocene wolf populations had more robust skulls and teeth than modern wolves, often with a shortened snout, a pronounced development of the temporalis muscle, and robust premolars. It is proposed that these features were specialized adaptations for the processing of carcass and bone associated with the hunting and scavenging of Pleistocene megafauna. Compared with modern wolves, some Pleistocene wolves showed an increase in tooth breakage similar to that seen in the extinct dire wolf. This suggests they either often processed carcasses, or that they competed with other carnivores and needed to consume their prey quickly. The frequency and location of tooth fractures in these wolves indicates they were habitual bone crackers like the modern spotted hyena.
Genomic studies suggest modern wolves and dogs descend from a common ancestral wolf population. A 2021 study found that the Himalayan wolf and the Indian plains wolf are part of a lineage that is basal to other wolves and split from them 200,000 years ago. Other wolves appear to share most of their common ancestry much more recently, within the last 23,000 years (around the peak and the end of the Last Glacial Maximum), originating from Siberia or Beringia. While some sources have suggested that this was a consequence of a population bottleneck, other studies have suggested that this a result of gene flow homogenising ancestry.
A 2016 genomic study suggests that Old World and New World wolves split around 12,500 years ago followed by the divergence of the lineage that led to dogs from other Old World wolves around 11,100–12,300 years ago. An extinct Late Pleistocene wolf may have been the ancestor of the dog, with the dog's similarity to the extant wolf being the result of genetic admixture between the two. The dingo, Basenji, Tibetan Mastiff and Chinese indigenous breeds are basal members of the domestic dog clade. The divergence time for wolves in Europe, the Middle East, and Asia is estimated to be fairly recent at around 1,600 years ago. Among New World wolves, the Mexican wolf diverged around 5,400 years ago.
Admixture with other canids.
In the distant past, there was gene flow between African wolves, golden jackals, and grey wolves. The African wolf is a descendant of a genetically admixed canid of 72% wolf and 28% Ethiopian wolf ancestry. One African wolf from the Egyptian Sinai Peninsula showed admixture with Middle Eastern grey wolves and dogs. There is evidence of gene flow between golden jackals and Middle Eastern wolves, less so with European and Asian wolves, and least with North American wolves. This indicates the golden jackal ancestry found in North American wolves may have occurred before the divergence of the Eurasian and North American wolves.
The common ancestor of the coyote and the wolf is admixed with a ghost population of an extinct unidentified canid. This canid was genetically close to the dhole and evolved after the divergence of the African hunting dog from the other canid species. The basal position of the coyote compared to the wolf has been proposed to be due to the coyote retaining more of the mitochondrial genome of this unidentified canid. Similarly, a museum specimen of a wolf from southern China collected in 1963 showed a genome that was 12–14% admixed from this unknown canid. In North America, some coyotes and wolves show varying degrees of past genetic admixture.
In more recent times, some male Italian wolves originated from dog ancestry, which indicates female wolves will breed with male dogs in the wild. In the Caucasus Mountains, ten percent of dogs including livestock guardian dogs, are first generation hybrids. Although mating between golden jackals and wolves has never been observed, evidence of jackal-wolf hybridization was discovered through mitochondrial DNA analysis of jackals living in the Caucasus Mountains and in Bulgaria. In 2021, a genetic study found that the dog's similarity to the extant grey wolf was the result of substantial dog-into-wolf gene flow, with little evidence of the reverse.
Description.
The wolf is the largest extant member of the family Canidae, and is further distinguished from coyotes and jackals by a broader snout, shorter ears, a shorter torso and a longer tail. It is slender and powerfully built, with a large, deeply descending rib cage, a sloping back, and a heavily muscled neck. The wolf's legs are moderately longer than those of other canids, which enables the animal to move swiftly, and to overcome the deep snow that covers most of its geographical range in winter, though more short-legged ecomorphs are found in some wolf populations. The ears are relatively small and triangular. The wolf's head is large and heavy, with a wide forehead, strong jaws and a long, blunt muzzle. The skull is in length and in width. The teeth are heavy and large, making them better suited to crushing bone than those of other canids, though they are not as specialized as those found in hyenas. Its molars have a flat chewing surface, but not to the same extent as the coyote, whose diet contains more vegetable matter. Females tend to have narrower muzzles and foreheads, thinner necks, slightly shorter legs, and less massive shoulders than males.
Adult wolves measure in length and at shoulder height. The tail measures in length, the ears in height, and the hind feet are . The size and weight of the modern wolf increases proportionally with latitude in accordance with Bergmann's rule. The mean body mass of the wolf is , the smallest specimen recorded at and the largest at . On average, European wolves weigh , North American wolves , and Indian and Arabian wolves . Females in any given wolf population typically weigh less than males. Wolves weighing over are uncommon, though exceptionally large individuals have been recorded in Alaska and Canada. In central Russia, exceptionally large males can reach a weight of .
Pelage.
The wolf has very dense and fluffy winter fur, with a short undercoat and long, coarse guard hairs. Most of the undercoat and some guard hairs are shed in spring and grow back in autumn. The longest hairs occur on the back, particularly on the front quarters and neck. Especially long hairs grow on the shoulders and almost form a crest on the upper part of the neck. The hairs on the cheeks are elongated and form tufts. The ears are covered in short hairs and project from the fur. Short, elastic and closely adjacent hairs are present on the limbs from the elbows down to the calcaneal tendons. The winter fur is highly resistant to the cold. Wolves in northern climates can rest comfortably in open areas at by placing their muzzles between the rear legs and covering their faces with their tail. Wolf fur provides better insulation than dog fur and does not collect ice when warm breath is condensed against it.
In cold climates, the wolf can reduce the flow of blood near its skin to conserve body heat. The warmth of the foot pads is regulated independently from the rest of the body and is maintained at just above tissue-freezing point where the pads come in contact with ice and snow. In warm climates, the fur is coarser and scarcer