Coywolf

Coywolf
Captive-bred F1 gray wolf-coyote hybrids, Wildlife Science Center in Forest Lake, Minnesota
Conservation status
Not evaluated (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Canidae
Genus:	Canis
Species:	C. latrans × C. lupus/lycaon/rufus

Coywolf (sometimes called woyote) 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's species. In one captive hybrid experiment, six F₁ hybrid pups from 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.

Compared with pure coyotes, Eastern wolf-coyote hybrids have been recorded forming more cooperative social groups and are generally less aggressive with each other while playing. Hybrids also reach sexual maturity when they are two years old, which is much later than occurs in pure coyotes.

Varieties

Gray wolf-coyote hybrids

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

Mexican gray wolf-coyote hybrids

Unlike eastern wolves and red wolves, the gray wolf rarely interbreeds with coyotes in the wild. Direct hybridizations between coyotes and gray wolves was never explicitly observed. Nevertheless, in a study that analyzed the molecular genetics of the coyotes as well as samples of historical red wolves and Mexican gray wolves from Texas, a few coyote genetic markers have been found in the historical samples of some isolated Mexican gray wolf individuals. Likewise, gray wolf Y-chromosomes have also been found in a few individual male Texan coyotes. This study suggested that although the Mexican gray wolf is generally less prone to hybridizations with coyotes, there may had been a few exceptional genetic exchanges with the Texan coyotes among individual gray wolves from historical remnants before the population was completely extirpated in Texas. In tests performed on a stuffed carcass of what was initially labelled a chupacabra, mitochondrial DNA analysis conducted by 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, the U.S. Department of Agriculture Wildlife Services conducted a captive breeding experiment at their National Wildlife Research Center Predator Research Facility in Logan, Utah. Using gray wolves from British Columbia and western coyotes, they produced six hybrids, making this the very first hybridization case between pure coyotes and northwestern gray wolves. The experiment, which used artificial insemination, was intended to determine whether or not the sperm of the larger gray wolves in the west was capable of fertilizing the egg cells of 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.

In 2015, a research team from the cell and microbiology department of Anoka-Ramsey Community College revealed that an F2 litter of two pups had been produced from two of the original hybrids. At the same time, it was also revealed that, despite the six F1's successful delivery from the same coyote, they were not all full siblings because multiple sperms from eight different northwestern gray wolves were used in their production. The successful production of the F2 litter, nonetheless, confirmed that hybrids of coyotes and northwestern gray wolves are just as fertile as hybrids of coyotes to eastern and red wolves. Both the F1 and F2 hybrids were found to be phenotypically intermediate between the western gray wolves and coyotes. Unlike the F1 hybrids, which were produced via artificial insemination, the F2 litter was produced from a natural breeding. The study also discovered through sequencing 16S ribosomal RNA encoding genes that the F1 hybrids all have an intestinal microbiome distinct from both parent species but were once reported to be present in some gray wolves. Moreover, analysis of their complementary DNA and ribosomal RNA revealed that the hybrids have very differential gene expressions compared to those in gray wolf controls.

Coydogs

Main article: Coydog

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 Michigan, 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 that reduced the number of suitable mates, thus facilitating coyote genes swamping into the eastern wolf population. Aside from posing a threat to a unique species, the resulting eastern wolf-coyote hybrids are too small to substitute for 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 led to the eastern wolf 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 on 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, rather than in the 1980s–1990s, when the majority of wolves had large amounts of coyote DNA.

Aside from the combinations of coyotes and eastern wolves making up most of the modern day eastern coyote's genepools, a study in 2013 by mammalian biologist Dr. Javier Monzón revealed that some of the coyotes in the northeastern USA also have mild domestic dogs (Canis lupus familiaris) and western Great Plains gray wolf (Canis lupus nubilus) influences in their genepool, thus suggesting that the eastern coyote is actually a four-in-one hybrid of coyotes, eastern wolves, western gray wolves, and dogs; and that the hybrids living in areas with higher white-tailed deer density often have higher degrees of wolf genes than those living in urban environments. The addition of domestic dog genes may have played a minor role in facilitating the eastern hybrids' adaptability to survive in human developed areas. The four-in-one hybrid theory was further explored in 2014, when Monzón and his team subsequently re-analyzed the tissue and SNP samples taken from 425 eastern coyotes to determine the degree of wolf and dog introgressions involved in each geographic range. The team discovered that the domestic dog allele averages 10% of the eastern coyote's genepool, while 26% is contributed by a cluster of both eastern wolves and western gray wolves. The remaining 64% matched mostly with coyotes. This analysis suggested that prior to the uniformity of its modern day genetic makeup, there may have been multiple swarms of genetic exchanges between the coyotes, feral dogs, and the two distinct wolf populations present in the Great Lakes region and that urban environments often favour coyote genes while the ones in the rural and deep forest areas maintain higher levels of wolf-content.

Great Lakes boreal hybrids

The taxonomy of the Great Lakes boreal wolf has long been debated by many North American mammalian biologists. Studies of the molecular-genetic literature on the wolf-like canids in the Great Lakes region have given rise to two disparate schools of thought: one group has argued that the animals are hybrids between western gray wolves and eastern wolves, the other that the hybrids derive from an extinct Pre-Columbian coyote population and a unique population of ecotype gray wolves. 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, 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 the decline 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. Fourteen 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.

See also

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

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)