Coywolf

Systematik

Coywolf is an informal term for a canid hybrid descended from coyotes and one of three other North American Canis species, the gray, eastern and red wolf. Coyotes are closely related to eastern and red wolves, having diverged 150,000–300,000 years ago and evolved side by side in North America, thus facilitating hybridization. In contrast, hybrids between coyotes and gray wolves, which are Eurasian in origin and diverged from coyotes 1–2 million years ago, are extremely rare. Such hybridization in the wild has only been confirmed in isolated gray wolf populations in the southern USA, while several specimens were produced in captivity via artificial insemination from sperm extracted from northwestern gray wolves introduced to female western coyotes.

Description

Hybrids of any combination tend to be larger than coyotes, and show behaviors intermediate between coyotes and the other parent species. In one captive hybrid experiment, six F₁ hybrid pups between a male northwestern gray wolf and a female coyote were measured shortly after birth with an average on their weights, total lengths, head lengths, body lengths, hind foot lengths, shoulder circumferences, and head circumferences compared with those on pure coyote pups at birth. The results found that despite being delivered by a female coyote, the hybrid pups at birth were much larger and heavier than regular coyote pups born and measured around the same time. At six months of age, these hybrids were closely monitored at the Wildlife Science Center. Executive Director Peggy Callahan at the facility states that the howls of these hybrids are said to start off much like regular gray wolves with a deep strong vocalization but changes partway into a coyote-like high pitched yipping.

Eastern wolf-coyote hybrids have been recorded to form more cooperative social groups than pure coyotes, and are generally less aggressive with each other while playing, in contrast to pure coyotes which are known to display higher levels of aggression and start mild fights preceding play. Hybrids also reach sexual maturity when they reach two years of age, much later than in pure coyotes.

Varieties

Gray wolf-coyote hybrids

F₁ hybrid coyote-gray wolf hybrid, conceived in captivity.

Mexican gray wolf-coyote hybrids

Despite the nature of hybridization between coyotes and gray wolves to be extremely rare, hybrids of southern coyotes and isolated Mexican gray wolves were speculated for a long time to have been roaming the south-central USA after the latter species was depleted from persecutions. However, their existences were not confirmed until 2007 through analysis from several specimens of large coyotes collected in the central and western Texas state. One analysis of controlled-region haplotypes of the mitochondrial DNA and sex chromosomes of Mexican gray wolves by Uppsala University detected the presence of coyote markers in some specimens. However, these markers were absent in captive Mexican gray wolf populations, thus suggesting that some male gray wolves from remnant wild populations began mating with female coyotes and coywolf hybrids, later backcrossing to other male wolves. Analysis on Texan coyote haplotypes also detected the presence of male gray wolf introgression, such as gray wolf Y-chromosomes in some of the male coyotes. In an extremely rare case, the study found that one coyote out of seventy individuals from Texas was discovered to carry a mtDNA haplotype derived from a female Mexican gray wolf, thus indicating that a male coyote had also managed to breed with a female Mexican gray wolf in the wild. The Mexican gray wolf may be the only gray wolf in the southern states besides domestic and feral dogs to have hybridized with coyotes. In tests performed on a taxidermied carcass of what was initially labelled as a chupacabra, mitochondrial DNA analysis conducted by the Texas State University showed that it was a coyote, though subsequent tests revealed that it was a coyote–gray wolf hybrid sired by a male Mexican gray wolf.

Northwestern gray wolf-coyote hybrids

In 2013, a captive breeding experiment conducted in the U.S. Department of Agriculture Wildlife Services National Wildlife Research Center Predator Research Facility in Logan, Utah between gray wolves from British Columbia and western coyotes produced six hybrids, making this the very first hybridization case between pure coyotes and northwestern gray wolves. The experiment used artificial insemination and was aimed with the intention of determining whether or not if the sperms of the larger gray wolves in the west are capable of fertilizing the egg cells in the western coyotes. Aside from the historical hybridizations between coyotes and the smaller Mexican gray wolves in the south as well as with eastern wolves and red wolves, grays wolves from the northwestern USA and western provinces of Canada are not known to interbreed with coyotes in the wild, thus prompting the experiment. The six resulting hybrids included four males and two females. At six months of age, the hybrids were closely monitored and were shown to display both physical and behavioral characteristics from both species, as well as some physical similarities to the eastern wolves, whose status as a distinct wolf species or as a genetically distinct subspecies of the gray wolf is controversial. Regardless, the result of this experiment concluded that northwestern gray wolves, much like the eastern wolves, red wolves, Mexican gray wolves, and domestic dogs, are capable of hybridizing with coyotes.Vorlage:Clear

Coydogs

Coydogs in Wyoming

Hybrids between coyotes and domestic dogs have been bred in captivity dating back to the Pre-Columbian Mexico. Other specimens were later produced by mammalian biologists mostly for research purposes. Although the latter species are not often considered wolves outside of the scientific community, domestic dogs are still subsumed into the gray wolf species hence coydogs are another biological sub-variations of hybrids between coyotes and gray wolves; the latter considered the domesticated form of Canis lupus. Some roaming primitive dogs in North America, such as the Carolina dogs from the south-eastern USA, are also suspected to have had historical genetic exchanges with coyotes. Unlike other gray wolf subspecies, dogs have been known to freely hybridize with any Canis that come into contact with them during the breeding seasons which gives them the potential to introgress into various wild wolf and coyote populations.

Eastern wolf-coyote hybrids

Eastern coyotes

Eastern coyote, an eastern wolf-coyote hybrid, West Virginia.

Eastern wolf-coyote hybrids, termed eastern coyotes, occur in New England, New York, New Jersey, Pennsylvania, Ontario, Quebec, New Brunswick, Nova Scotia, and Newfoundland and Labrador. The eastern wolf is particularly susceptible to hybridization with the coyote, due to its close relationship to it and its ability to bridge gene flow between both coyotes and gray wolves. Furthermore, hunting over a period of 400 years caused a population decline which reduced the number of suitable mates, thus facilitating coyote gene swamping into the eastern wolf population. Aside from posing a threat to a unique species, the resulting eastern wolf-coyote hybrids are too small in size to substitute pure eastern wolves as apex predators of moose and deer. The main nucleus of pure eastern wolves is currently concentrated within Algonquin Provincial Park. This susceptibility to hybridization lead to the eastern wolf to being listed as Special Concern under the Canadian Committee on the Status of Endangered Wildlife (COSEWIC) and with the Committee on the Status of Species at Risk in Ontario (COSSARO). By 2001, protection was extended to eastern wolves occurring in the outskirts of the Park, thus no longer depriving Park eastern wolves of future pure-blooded mates. By 2012, the genetic composition of the Park's eastern wolves was roughly restored to what it was in the mid-1960s than in the 1980s–1990s, when the majority of wolves had large amounts of coyote DNA.Vorlage:Clear

Great Lakes boreal hybrids

The taxonomy of the Great Lakes boreal wolf has long been debated by many North American mammalian biologists. Two disparate schools of thoughts studying the molecular-genetic literature on the wolf-like canids in the Great Lakes region have argued that the animals are hybrids between western gray wolves and eastern wolves or hybrids between an extinct Pre-Columbian coyote population and a unique population of ecotype gray wolves respectively. The latter group asserts that the eastern wolf is a genetically distinct subspecies of the gray wolf with mild coyote introgression. Evolutionary biologists who analyzed 48,000 single nucleotide polymorphism detected patterns of gray wolf and coyote admixture in the Great Lakes boreal wolves and thus interpreted these findings as evidences of ancient hybridizations between gray wolves and coyotes. Those who were critical of the genome research's interpretation, however, re-analyzed the data and compared them to samples taken from eastern wolves in Algonquin Provincial Park. This group found that some of the gray wolf genes were also admixed with eastern wolves and interpreted the coyote-like haplotypes as eastern wolf DNA. However, subsequent analysis on mtDNA, autosomal and sex chromosomes suggests that the wolves in the Great Lakes boreal forests are actually hybrids of all three Canis species. Since pure gray wolves in the wild rarely interbreed with pure coyotes, it is suspected that earlier hybrids between gray and eastern wolves from the western Great Lakes boreal forests may had hybridized with hybrids between eastern wolves and coyotes on the eastern half and thus forming the modern day hybrids in the Great Lakes region.

Red wolf-coyote hybrids

Due to intensive persecution, forest clearing, road building, and perhaps declines in deer populations throughout the 1900s, red wolves were eliminated from most of their historic range, being reduced to a small population in Louisiana and Texas by the 1960s. This limited range was also occupied by coyotes, which began to hybridize with the remaining red wolves, to the point that the U.S. Fish and Wildlife Service listed the species as endangered in 1967. The Service initiated a captive breeding program in 1973, with over 400 wild canids being captured for the purpose, though only 10% of this stock was determined to be of pure red wolf stock. 14 of the captured animals were ultimately released into northeastern North Carolina in 1986, though coyotes began to colonize the area in the early 1990s, resulting in the creation of hybrid offspring. The Wildlife Service's current management strategy consists of sterilizing hybrids, though the identification of hybrids with more than 50% red wolf ancestry is difficult based on appearance alone, so they are instead identified through assignment tests based on microsatellite loci. Vorlage:Clear

See also

• Canid hybrid
• Jackal-dog hybrid
• Wolf-dog hybrid
• Coydog

Further reading

• J.R. Adams, B.T. Kelly, L.P. Waits: Using faecal DNA sampling and GIS to monitor hybridization between red wolves (Canis rufus) and coyote (Canis latrans). In: Mol. Ecol. 12. Jahrgang, 2003, S. 2175–2186, doi:10.1046/j.1365-294x.2003.01895.x. 
• H. McCarley: The taxonomic status of wild Canis (Canidae) in the south central United States. In: Southwest. Nat. 1962. Jahrgang, Nr. 7, S. 227–235. 
• R.K. Wayne, S.M. Jenks: Mitochondrial DNA analysis implying extensive hybridization of the endangered red wolf Canis rufus. In: Nature. 351. Jahrgang, Nr. 6327, 1991, S. 565–568, doi:10.1038/351565a0. 

External links

• The complicated science of studying coyotes and hybrid species: Mysteries That Howl and Hunt
• Interbreeding Threatens Rare Species, Experts Say
• Eastern Coyote/Coywolf Research
• "Meet the Coywolf" episode of PBS' Nature series (premiere 22 Jan 2014)