Editing Red wolf (section)

=== Taxonomic debate ===
When European settlers first arrived to North America, the coyote's range was limited to the western half of the continent. They existed in the arid areas and across the open plains, including the prairie regions of the midwestern states. Early explorers found some in Indiana and Wisconsin. From the mid-1800s onward, coyotes began expanding beyond their original range.<ref name=nowak1979/>

The taxonomic debate regarding North American wolves can be summarised as follows:
{{Blockquote|There are two prevailing evolutionary models for North American ''Canis'':
;(i) a two-species model: that identifies '''grey wolves''' (''C.&nbsp;lupus'') and (western) '''coyotes''' (''Canis latrans'') as distinct species that gave rise to various hybrids, including the Great Lakes-boreal wolf (also known as Great Lakes wolf), the eastern coyote (also known as Coywolf / brush wolf / tweed wolf), the red wolf, and the eastern (Algonquin) wolf;
and
;(ii) a three-species model: that identifies the '''grey wolf''', western '''coyote''', and '''eastern wolf''' (''C.&nbsp;lycaon'') as distinct species, where Great Lakes-boreal wolves are the product of grey wolf × eastern wolf hybridization, eastern coyotes are the result of eastern wolf × western coyote hybridization, and red wolves are considered historically the same species as the eastern wolf, although their contemporary genetic signature has diverged owing to a bottleneck associated with captive breeding.<ref name=rutledge2015/>
}}

==== Fossil evidence ====
The [[paleontologist]] Ronald M. Nowak notes that the oldest fossil remains of the red wolf are 10,000&nbsp;years old and were found in Florida near [[Melbourne, Florida|Melbourne]], [[Brevard County, Florida|Brevard County]], Withlacoochee River, [[Citrus County, Florida|Citrus County]], and [[Devil's Den Cave]], [[Levy County, Florida|Levy County]]. He notes that there are only a few, but questionable, fossil remains of the gray wolf found in the southeastern states. He proposes that following the extinction of the [[dire wolf]], the coyote appears to have been displaced from the southeastern US by the red wolf until the last century, when the extirpation of wolves allowed the coyote to expand its range. He also proposes that the ancestor of all North American and Eurasian wolves was ''[[Canis variabilis#Canis mosbachensis|C.&nbsp;mosbachensis]]'', which lived in the [[Middle Pleistocene]] 700,000–300,000&nbsp;years ago.<ref name=nowak2002/>

''C.&nbsp;mosbachensis'' was a wolf that once lived across Eurasia before going extinct. It was smaller than most North American wolf populations and smaller than ''C.&nbsp;rufus'', and has been described as being similar in size to the small [[Indian wolf]], ''Canis lupus pallipes''. He further proposes that ''C.&nbsp;mosbachensis'' invaded North America where it became isolated by the later glaciation and there gave rise to ''C.&nbsp;rufus''. In Eurasia, ''C.&nbsp;mosbachensis'' evolved into ''C.&nbsp;lupus'', which later invaded North America.<ref name=nowak2003/>{{rp|242}}

The [[paleontologist]] and expert on the genus ''Canis''{{'}} natural history, [[Xiaoming Wang (paleontologist)|Xiaoming Wang]], looked at red wolf fossil material but could not state if it was, or was not, a separate species. He said that Nowak had put together more [[morphometric]] data on red wolves than anybody else, but Nowak's statistical analysis of the data revealed a red wolf that is difficult to deal with. Wang proposes that studies of [[ancient DNA]] taken from fossils might help settle the debate.<ref name=beeland2013/> In 2009, Tedford, Wang and Taylor reclassified the purported red wolf fossils as ''[[Canis armbrusteri]]'' and ''[[Canis edwardii]]''.<ref>{{cite journal |title=Phylogenetic systematics of the North American fossil Caninae (Carnivora: Canidae) |year=2009 |first1=Richard |last1=Tedford |author1-link=Richard H. Tedford |first2=Xiaoming |last2=Wang |author2-link=Xiaoming Wang (paleontologist) |first3=Beryl E. |last3=Taylor |journal=[[Bulletin of the American Museum of Natural History]] |volume=325 |pages=1–218 |doi=10.1206/574.1 |hdl=2246/5999 |s2cid=83594819 |url=https://bioone.org/journals/bulletin-of-the-american-museum-of-natural-history/volume-2009/issue-325/574.1/Phylogenetic-Systematics-of-the-North-American-Fossil-Caninae-Carnivora/10.1206/574.1.full}}</ref>

==== Morphological evidence ====
[[File:John Woodhouse Audubon - Red Texas Wolf (Canis Lupus) - Google Art Project.jpg|thumb|Audubon's depiction of the red wolf (1851)]]
[[File:The Wolves of North America (1944) C. lupus, rufus & latrans.jpg|thumb|Skulls of North American canines, with the red wolf in the center]]

In 1771, the English naturalist [[Mark Catesby]] referred to Florida and the Carolinas when he wrote that "The Wolves in America are like those of Europe, in shape and colour, but are somewhat smaller." They were described as being more timid and less voracious.<ref name=catesby1771/> In 1791 the American naturalist [[William Bartram]] wrote in his book ''[[Bartram's Travels|Travels]]'' about a wolf which he had encountered in Florida that was larger than a dog, but was black in contrast to the larger yellow-brown wolves of Pennsylvania and Canada.<ref name=phillips2003/><ref name=bartram1791/> In 1851 the naturalists [[John James Audubon]] and [[John Bachman]] described the "Red Texan Wolf" in detail. They noted that it could be found in Florida and other southeastern states, but it differed from other North American wolves and named it ''Canis lupus rufus''. It was described as being more fox-like than the gray wolf, but retaining the same "sneaking, cowardly, yet ferocious disposition".<ref name=audubon1851/>

In 1905, the mammalogist [[Vernon Orlando Bailey|Vernon Bailey]] referred to the "Texan Red Wolf" with the first use of the name ''Canis rufus''.<ref name=bailey1905/> In 1937 the zoologist [[Edward Alphonso Goldman|Edward Goldman]] undertook a [[Morphology (biology)|morphological]] study of southeastern wolf specimens. He noted that their skulls and dentition differed from those of gray wolves and closely approached those of coyotes. He identified the specimens as all belonging to the one species which he referred to as ''Canis rufus''.<ref name=goldman1937/><ref name=goldman1944/> Goldman then examined a large number of southeastern wolf specimens and identified three subspecies, noting that their colors ranged from black, gray, and cinnamon-buff.<ref name=goldman1944/>

It is difficult to distinguish the red wolf from a red wolf × coyote hybrid.<ref name=phillips2003/> During the 1960s, two studies of the skull morphology of wild ''Canis'' in the southeastern states found them to belong to the red wolf, the coyote, or many variations in between. The conclusion was that there has been recent massive hybridization with the coyote.<ref name=mccarley1962/><ref name=paradiso1968/> In contrast, another 1960s study of ''Canis'' morphology concluded that the red wolf, eastern wolf, and domestic dog were closer to the gray wolf than the coyote, while still remaining clearly distinctive from each other. The study regarded these 3&nbsp;canines as subspecies of the gray wolf. However, the study noted that "red wolf" specimens taken from the edge of their range which they shared with the coyote could not be attributed to any one species because the cranial variation was very wide. The study proposed further research to ascertain if hybridization had occurred.<ref name=lawrence1967/><ref name=lawrence1975/>

In 1971, a study of the skulls of ''C.&nbsp;rufus'', ''C.&nbsp;lupus'' and ''C.&nbsp;latrans'' indicated that ''C.&nbsp;rufus'' was distinguishable by being in size and shape midway between the gray wolf and the coyote. A re-examination of museum canine skulls collected from central Texas between 1915 and 1918 showed variations spanning from ''C.&nbsp;rufus'' through to ''C.&nbsp;latrans''. The study proposes that by 1930 due to human habitat modification, the red wolf had disappeared from this region and had been replaced by a [[hybrid swarm]]. By 1969, this hybrid swarm was moving eastwards into eastern Texas and Louisiana.<ref name=paradiso1971/>

In the late 19th century, sheep farmers in [[Kerr County, Texas]], stated that the coyotes in the region were larger than normal coyotes, and they believed that they were a gray wolf and coyote cross.<ref name=nowak1979/> In 1970, the wolf mammalogist [[L. David Mech]] proposed that the red wolf was a hybrid of the gray wolf and coyote.<ref name=mech1970/> However, a 1971 study compared the [[cerebellum]] within the brain of six ''Canis'' species and found that the cerebellum of the red wolf indicated a distinct species, was closest to that of the gray wolf, but in contrast indicated some characteristics that were more primitive than those found in any of the other ''Canis'' species.<ref name=atkins1971/> In 2014, a three-dimensional [[Morphometrics#Landmark-based geometric morphometrics|morphometrics]] study of ''Canis'' species accepted only six red wolf specimens for analysis from those on offer, due to the impact of hybridization on the others.<ref name=schmitt2014/>

==== DNA studies ====
Different DNA studies may give conflicting results because of the specimens selected, the technology used, and the assumptions made by the researchers.<ref name=boyko2009/>{{efn| Any one from a panel of [[genetic marker]]s can be chosen for use in a study. The techniques used to [[DNA extraction|extract]], [[DNA sequencing|locate]] and [[DNA analysis|compare]] genetic sequences can be applied using advances in technology, which allows researchers to observe longer lengths of [[Base pair#Length measurements|base pairs]] that provide more data to give better [[phylogenetic]] resolution.<ref name=pang2009/>}}

[[Phylogenetic trees]] compiled using different [[genetic markers]] have given conflicting results on the relationship between the wolf, dog and coyote. One study based on [[Single-nucleotide polymorphism|SNPs]]<ref name=cronin2014/> (a single [[mutation]]), and another based on [[nuclear gene]] sequences<ref name=bardeleben2005/> (taken from the [[cell nucleus]]), showed dogs clustering with coyotes and separate from wolves. Another study based on SNPS showed wolves clustering with coyotes and separate from dogs.<ref name=gray2010/> Other studies based on a number of markers show the more widely accepted result of wolves clustering with dogs separate from coyotes.<ref name=vila1997/><ref name=wayne2012/> These results demonstrate that caution is needed when interpreting the results provided by genetic markers.<ref name=cronin2014/>

===== Genetic marker evidence =====
In 1980, a study used [[gel electrophoresis]] to look at fragments of DNA taken from dogs, coyotes, and wolves from the red wolf's core range. The study found that a unique [[allele]] (expression of a [[gene]]) associated with [[Lactate dehydrogenase]] could be found in red wolves, but not dogs and coyotes. The study suggests that this allele survives in the red wolf. The study did not compare gray wolves for the existence of this allele.<ref name=ferrell1980/>

[[Mitochondrial DNA]] (mDNA) passes along the maternal line and can date back thousands of years.<ref name=beeland2013/> In 1991, a study of red wolf mDNA indicates that red wolf [[genotypes]] match those known to belong to the gray wolf or the coyote. The study concluded that the red wolf is either a wolf × coyote hybrid or a species that has hybridized with the wolf and coyote across its entire range. The study proposed that the red wolf is a southeastern occurring subspecies of the gray wolf that has undergone hybridization due to an expanding coyote population; however, being unique and threatened that it should remain protected.<ref name=wayne1991/> This conclusion led to debate for the remainder of the decade.<ref name=gittleman1991/><ref name=nowak1992/><ref name=dowling1992/><ref name=roy1994/><ref name=brewster1995/><ref name=nowak1995/><ref name=nowak1995a/><ref name=roy1996/><ref name=nowak1998/><ref name=wayne1998/><ref name=reich1999/>

{{cladogram
|title=Proposed phylogenetic tree of wolf evolution
|cladogram=
  {{clade
  |label1 = Ancestral Canid{{br}}(1-2 million years ago)
  |1 =
    {{clade
    |1 =
      {{clade
      |1 = [[Coyote]]
      |2 =
        {{clade
        |1 = [[Red wolf]]
        |2 = [[Eastern wolf]]
        }}
      }}
    |label2 = [[Gray wolf]]
    |grouplabel2 = [[Subspecies of Canis lupus|Gray wolf subspecies]]
    |bar2 = grey
    |2 =
      {{clade
      |1 = {{clade}}
      |2 = {{clade}}
      }}
    }}
  }}
}}

In 2000, a study looked at red wolves and [[Eastern wolf|eastern Canadian wolves]]. The study agreed that these two wolves readily hybridize with the coyote. The study used eight [[microsatellites]] (genetic markers taken from across the [[genome]] of a specimen). The phylogenetic tree produced from the genetic sequences showed red wolves and eastern Canadian wolves clustering together. These then clustered next closer with the coyote and away from the gray wolf. A further analysis using mDNA sequences indicated the presence of coyote in both of these two wolves, and that these two wolves had diverged from the coyote 150,000–300,000&nbsp;years ago. No gray wolf sequences were detected in the samples. The study proposes that these findings are inconsistent with the two wolves being subspecies of the gray wolf, that red wolves and eastern Canadian wolves evolved in North America after having diverged from the coyote, and therefore they are more likely to hybridize with coyotes.<ref name=wilson2000/>

In 2009, a study of eastern Canadian wolves using microsatellites, mDNA, and the paternally-inherited [[yDNA]] markers found that the eastern Canadian wolf was a unique [[ecotype]] of the gray wolf that had undergone recent hybridization with other gray wolves and coyotes. It could find no evidence to support the findings of the earlier 2000 study regarding the eastern Canadian wolf. The study did not include the red wolf.<ref name=koblmuller2009/>

In 2011, a study compared the genetic sequences of 48,000&nbsp;[[single nucleotide polymorphisms]] ([[mutations]]) taken from the genomes of canids from around the world. The comparison indicated that the red wolf was about 76% coyote and 24% gray wolf with hybridization having occurred 287–430&nbsp;years ago. The eastern wolf was 58% gray wolf and 42% coyote with hybridization having occurred 546–963&nbsp;years ago. The study rejected the theory of a common ancestry for the red and eastern wolves.<ref name=beeland2013/><ref name=vonholdt2011/> However the next year, a study reviewed a subset of the 2011 study's [[Single-nucleotide polymorphism]] (SNP) data and proposed that its methodology had skewed the results and that the red and eastern wolves are not hybrids but are in fact the same species separate from the gray wolf.<ref name=beeland2013/><ref name=rutledge2012a>{{cite journal |last1=Rutledge |first1=Linda Y. |last2=Wilson |first2=Paul J. |last3=Klütsch |first3=Cornelya F.C. |last4=Patterson |first4=Brent R. |last5=White |first5=Bradley N. |year=2012 |url=http://people.trentu.ca/brentpatterson/index_files/Rutledge%20et%20al%202012%20-%20conservation%20genomics%20in%20perspective.pdf |title=Conservation genomics in perspective: A holistic approach to understanding ''Canis'' evolution in North America |journal=Biological Conservation |volume=155 |pages=186–192 |doi=10.1016/j.biocon.2012.05.017 |bibcode=2012BCons.155..186R |access-date=2013-07-01}}</ref> The 2012 study proposed that there are three true ''Canis'' species in North America: The gray wolf, the western coyote, and the red wolf / eastern wolf. The eastern wolf was represented by the Algonquin wolf. The Great Lakes wolf was found to be a hybrid of the eastern wolf and the gray wolf. Finally, the study found the eastern coyote itself to be yet another a hybrid between the western coyote and the eastern (Algonquin) wolf (for more on eastern North American wolf-coyote hybrids, ''see'' [[coywolf]]).<ref name=rutledge2012a/>

Also in 2011, a scientific [[literature review]] was undertaken to help assess the taxonomy of North American wolves. One of the findings proposed was that the eastern wolf is supported as a separate species by morphological and genetic data. Genetic data supports a close relationship between the eastern and red wolves, but not close enough to support these as one species. It was "likely" that these were the separate descendants of a common ancestor shared with coyotes. This review was published in 2012.<ref name=chambers2012/> In 2014, the [[National Center for Ecological Analysis and Synthesis]] was invited by the [[United States Fish and Wildlife Service]] to provide an independent review of its proposed rule relating to gray wolves. The center's panel findings were that the proposed rule depended heavily upon a single analysis contained in a scientific literature review by Chambers ''et al''. (2011 ),{{citation needed|date=November 2023}} that that study was not universally accepted, that the issue was "not settled", and that the rule does not represent the "best available science".<ref name=dumbacher2014/>

Brzeski ''et al''. (2016)<ref name=brzeski2016/> conducted an mDNA analysis of three ancient (300–1,900&nbsp;years old) wolf-like samples from the southeastern United States found that they grouped with the coyote clade, although their teeth were wolf-like. The study proposed that the specimens were either coyotes and this would mean that coyotes had occupied this region continuously rather than intermittently, a North American evolved red wolf lineage related to coyotes, or an ancient coyote–wolf hybrid. Ancient hybridization between wolves and coyotes would likely have been due to natural events or early human activities, not landscape changes associated with European colonization because of the age of these samples.<ref name=brzeski2016/> Coyote–wolf hybrids may have occupied the southeastern United States for a long time, filling an important niche as a medium-large predator.<ref name=roy1996/><ref name=brzeski2016/>

===== Whole-genome evidence =====
[[File:Red Wolf (1980).png|right|thumb|A red wolf in the forest]]
In July 2016, a [[Whole genome sequencing|whole-genome]] DNA study proposed, based on the assumptions made, that all of the North American wolves and coyotes diverged from a common ancestor less than 6,000–117,000&nbsp;years ago. The study also indicated that all North America wolves have a significant amount of coyote ancestry and all coyotes some degree of wolf ancestry, and that the red wolf and Great Lakes region wolf are highly [[Genetic admixture|admixed]] with different proportions of gray wolf and coyote ancestry. One test indicated a wolf/coyote divergence time of 51,000&nbsp;years before present that matched other studies indicating that the extant wolf came into being around this time. Another test indicated that the red wolf diverged from the coyote between 55,000 and 117,000&nbsp;years before present and the Great Lakes region wolf 32,000&nbsp;years before present. Other tests and modelling showed various divergence ranges and the conclusion was a range of less than 6,000 and 117,000&nbsp;years before present. The study found that coyote ancestry was highest in red wolves from the southeast of the United States and lowest among the Great Lakes region wolves.

The theory proposed was that this pattern matched the south-to-north disappearance of the wolf due to European colonization and its resulting loss of habitat. Bounties led to the extirpation of wolves initially in the southeast, and as the wolf population declined wolf-coyote admixture increased. Later, this process occurred in the Great Lakes region with the influx of coyotes replacing wolves, followed by the expansion of coyotes and their hybrids across the wider region.<ref name=vonholdt2016/><ref>{{cite journal |doi=10.1126/science.aag0699 |title=How do you save a wolf that's not really a wolf? |journal=Science |year=2016 |last1=Morell |first1=Virginia}}</ref> The red wolf may possess some genomic elements that were unique to gray wolf and coyote lineages from the American South.<ref name=vonholdt2016/> The proposed timing of the wolf/coyote divergence conflicts with the finding of a coyote-like specimen in strata dated to 1 million years before present,<ref name=wang2008/> and red wolf fossil specimens dating back 10,000&nbsp;years ago.<ref name=nowak2002/> The study concluded by stating that because of the extirpation of gray wolves in the American Southeast, "the reintroduced population of red wolves in eastern North Carolina is doomed to genetic swamping by coyotes without the extensive management of hybrids, as is currently practiced by the USFWS."<ref name=vonholdt2016/>

In September&nbsp;2016, the USFWS announced a program of changes to the red wolf recovery program<ref name=fws2016a/> and "will begin implementing a series of actions based on the best and latest scientific information". The service will secure the captive population which is regarded as not sustainable, determine new sites for additional experimental wild populations, revise the application of the existing experimental population rule in North Carolina, and complete a comprehensive Species Status Assessment.<ref name=fws2016b/>

In 2017, a group of canid researchers challenged the recent finding that the red wolf and the eastern wolf were the result of recent coyote-wolf hybridization. The group highlight that no testing had been undertaken to ascertain the time period that hybridization had occurred and that, by the previous study's own figures, the hybridization could not have occurred recently but supports a much more ancient hybridization. The group found deficiencies in the previous study's selection of specimens and the findings drawn from the different techniques used. Therefore, the group argues that both the red wolf and the eastern wolf remain genetically distinct North American taxa.<ref name=hohenlohe2017/> This was rebutted by the authors of the earlier study.<ref name=vonholdt2017/> Another study in late 2018 of wild canids in southwestern [[Louisiana]] also supported the red wolf as a separate species, citing distinct red wolf DNA within hybrid canids.<ref name=":4">{{Cite journal |last1=Murphy |first1=Sean M. |last2=Adams |first2=Jennifer R. |last3=Cox |first3=John J. |last4=Waits |first4=Lisette P. |title=Substantial red wolf genetic ancestry persists in wild canids of southwestern Louisiana |journal=Conservation Letters |language=en |issue=2 |pages=e12621 |doi=10.1111/conl.12621 |issn=1755-263X |year=2018|volume=12 |doi-access=free }}</ref>

In 2019, a [[literature review]] of the previous studies was undertaken by the [[National Academies of Sciences, Engineering, and Medicine]]. The position of the National Academies is that the historical red wolf forms a valid taxonomic species, the modern red wolf is distinct from wolves and coyotes, and modern red wolves trace some of their ancestry to historic red wolves. The species ''Canis rufus'' is supported for the modern red wolf, unless genomic evidence from historical red wolf specimens changes this assessment, due to a lack of continuity between the historic and the modern red wolves.<ref>{{cite book |doi=10.17226/25351 |pmid=31211533 |title=Evaluating the Taxonomic Status of the Mexican Gray Wolf and the Red Wolf |year=2019 |isbn=978-0-309-48824-2 |department=Board on Life Sciences |publisher=National Academies of Sciences and Engineering|last1=National Academies Of Sciences |first1=Engineering |s2cid=134662152 }}</ref>

===== Wolf genome =====
Genetic studies relating to wolves or dogs have inferred phylogenetic relationships based on the only reference genome available, that of the [[Boxer (dog)|Boxer dog]]. In 2017, the first reference genome of the wolf ''Canis lupus lupus'' was mapped to aid future research.<ref name=gopalakrishnan2017/> In 2018, a study looked at the genomic structure and admixture of North American wolves, wolf-like canids, and coyotes using specimens from across their entire range that mapped the largest dataset of nuclear genome sequences against the wolf reference genome. The study supports the findings of previous studies that North American gray wolves and wolf-like canids were the result of complex gray wolf and coyote mixing. A [[Greenland wolf|polar wolf from Greenland]] and a coyote from Mexico represented the purest specimens. The coyotes from Alaska, California, Alabama, and Quebec show almost no wolf ancestry. Coyotes from Missouri, Illinois, and Florida exhibit 5–10% wolf ancestry. There was 40%:60% wolf to coyote ancestry in red wolves, 60%:40% in Eastern timber wolves, and 75%:25% in the Great Lakes wolves. There was 10% coyote ancestry in Mexican wolves and Atlantic Coast wolves, 5% in Pacific Coast and [[History of wolves in Yellowstone|Yellowstone wolves]], and less than 3% in Canadian archipelago wolves.<ref name=sinding2018/>

The study shows that the genomic ancestry of red, eastern timber and Great Lakes wolves were the result of admixture between modern gray wolves and modern coyotes. This was then followed by development into local populations. Individuals within each group showed consistent levels of coyote to wolf inheritance, indicating that this was the result of relatively ancient admixture. The eastern timber wolf ([[Algonquin Provincial Park]]) is genetically closely related to the Great Lakes wolf (Minnesota, Isle Royale National Park). If a third canid had been involved in the admixture of the North American wolf-like canids, then its genetic signature would have been found in coyotes and wolves, which it has not.<ref name=sinding2018/>

Gray wolves suffered a species-wide [[population bottleneck]] (reduction) approximately 25,000 YBP during the Last Glacial Maximum. This was followed by a single population of modern wolves expanding out of a [[Beringia#Refugium|Beringia refuge]] to repopulate the wolf's former range, replacing the remaining [[Megafaunal wolf|Late Pleistocene wolf]] populations across Eurasia and North America as they did so.<ref name=Loog2018/><ref name=Schweizer2020/> This implies that if the coyote and red wolf were derived from this invasion, their histories date only tens of thousands and not hundreds of thousands of years ago, which is consistent with other studies.<ref name=Schweizer2020/>

The Endangered Species Act provides protection to endangered species, but does not provide protection for endangered admixed individuals, even if these serve as reservoirs for extinct genetic variation. Researchers on both sides of the red wolf debate argue that admixed canids warrant full protection under this Act.<ref name=heppenheimer2018/><ref name=vonholdt2016/>

===== Separate species that can be strengthened from hybrids =====
In 2020, a study conducted DNA sequencing of [[Canis|canines]] across southeastern US to detect those with any red wolf ancestry. The study found that red wolf ancestry exists in the coyote populations of southwestern Louisiana and southeastern Texas, but also newly detected in North Carolina. The red wolf ancestry of these populations possess unique red wolf alleles not found in the current captive red wolf population. The study proposes that the expanding coyotes admixed with red wolves to gain genetic material that was suited to the southeastern environment and would aid their adaptation to it, and that surviving red wolves admixed with coyotes because the red wolves were suffering from inbreeding.<ref name=Heppenheimer2020/>

In 2021, a study conducted DNA sequencing of canines across the remnant red wolf hybrid zone of southwestern Louisiana and southeastern Texas. The study found red wolf ancestry in the coyote genomes which increases up to 60% in a westward gradient. This was due to introgression from the remnant red wolf population over the past 100 years. The study proposes that coyotes expanded into the [[Gulf of Mexico|gulf]] region and admixed with red wolves prior to the red wolf going extinct in the wild due to loss of habitat and persecution. In the past two decades the hybrid region has expanded. The study presented the genetic evidence that the red wolf is a separate species, based on the structure of one of the [[Locus (genetics)|loci]] of its [[X-chromosome]] which is accepted as a marker for distinct species. As such, the study suggested that the introgressed red wolf ancestry could be de-introgressed back as a basis for breeding further red wolves from the hybrids.<ref name=Vonholdt2021/>

===== Pre-dates the coyote in North America =====
In 2021, a study of mitochondrial genomes sourced from specimens dated before the 20th century revealed that red wolves could be found across North America. With the arrival of the gray wolf between 80,000 and 60,000 years ago, the red wolf's range shrank to the eastern forests and California, and the coyote replaced the red wolf mid-continent between 60,000 and 30,000 years ago. The coyote expanded into California at the beginning of the [[Holocene]] era 12,000–10,000 years ago and admixed with the red wolf, phenotypically replacing them. The study proposes that the red wolf may pre-date the coyote in North America.<ref name=Sacks2021/>