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|Wolf Genome Study Proves Red Wolf Is Not A Unique Species|
|Tweet Topic Started: Jun 27 2012, 02:43 AM (2,155 Views)|
|MightyKharza||Jun 27 2012, 02:43 AM Post #1|
The creature formerly known as “the red wolf”
Long-time readers of this blog know that I have long been skeptical of the classification of the red wolf as a distinct species.
Because this animal is rather large and hunts in packs and because it closely resembles the primitive pallipes wolf of the Middle East and India, I guessed that it was an early offshoot of the Canis lupus species. I never bought into the oft-promoted theory that this wolf was a primitive wolf that represented an even more ancient origin that the Canis mosbachensis and Canis lupus lineage of the Old World.
This theory, promoted by Ron Nowak and popularized throughout the wildlife conservation world (including the US Fish and Wildlife Service), holds that the red wolf is a derivative of Canis edwardii, an early North American member of the genus Canis that was roughly similar to the red wolf in size and general distribution. Nowak performed any number of skull measurements to prove his thesis. Anyone familiar with dog and wolf anatomy knows are actually among the most variable features within a population. Everyone has seen litters of dogs in which littermates have different head shapes. Even in purebred litters, one can see puppies that have quite a bit of variance in head-type. For this reason, many conformation breeders of so-called “head breeds” have a very hard time fixing a consistent head within their lines. This variance in head shape also occurs in wolves, which is one reason why the Goyet cave ”dog” is so disputed. Is its short muzzle the result of domestication or natural variance within a wolf population?
Another factor drove me to question the red wolf’s validity as a species. I greatly enjoyed Bruce Hampton’s The Great American Wolf, which is a history of man’s extermination of wolves on this continent. On page 166, Hampton provides an image of red wolf that was trapped in 1929 at Gillham, Arkansas.:
The wolf’s jaws were bound with wire. It was then tied up to a stake to meet its fate. Either the dogs were going to be set upon it, or it was going to be left tied up to die from dehydration. Unfortunately, this image is not available in the preview, but what struck me about it is that this wolf looked nothing like the creatures that are claimed to be red wolves now. The animal had smaller ears and a broader muzzle– much like one would expect in an Iranian wolf or Spanish wolf. It was nothing like a coyote.
The ones I’ve seen in zoos have all had very strong coyote features– large ears and a narrower muzzle– but those same features can also been seen in Indian wolves, which are thought to be among the most ancient of extant wolf lineages. Although I had skepticism about the Canis edwardii theory, I was more willing to accept that the red wolf was somehow related to the Indian wolf, for both would be very similar to the old primitive Canis lupus wolves from which the entire Holarctic wolf species descends.
The original mtDNA studies performed by Dr.Robert Wayne of UCLA found that all the red wolves in his samples had coyote or “gray wolf” mtDNA sequences. The majority of had coyote mtDNA. The wolves of Minnesota and Quebec also had coyote mtDNA, which Wayne contended came from hybridization with coyotes. This finding caused an uproar in wolf conservation circles. This particular finding came out just seven years after the first red wolves were released into the Alligator River National Wildlife Refuge in North Carolina. The US Fish and Wildlife Service was investing heavily in ensuring that his population thrived and remained free from the taint of coyote blood. Even now, much the work in red wolf conservation is trapping coyotes in red wolf range. For some reason, the released red wolves and the colonizing coyotes just loved each other.
Wayne was not popular in the red wolf conservation community. Nowak wrote a rebuttal to Wayne in which his biggest argument is that there never were any coyotes in the eastern part of North America. Then Wilson released several comparative studies of red wolves and those of Algonquin Park in Ontario. These Algonquin Park wolves were main study population of John and Mary Theberge. These were smaller, more “coyote-like” wolves, that had come to specialize on hunting beavers in their native range. Because of their appearance and because they were thought to have coyote mtDNA, Paul Wilson’s team decided to compare microsatellites in the DNA of Algonquin wolves, red wolves, coyotes, and Western “gray” wolves. The Algonquin and red wolves were found to have a divergent lineage from either Western “gray” wolves and coyotes. Those findings appeared to vindicate Nowak’s morphological studies that showed the red wolf to be part of an ancient North American lineage of wolf that derived from Canis edwardii (or something wholly North American), not Canis mosbachensis or Canis lupus.
I thought the microsatellite finding was still unconvincing. Perhaps these wolves were derived from a very early offshoot of Canis mosbachensis or early Canis lupus that invaded North America before the main Holarctic wolf lineages had developed.
I was waiting for something more.
Well, something more has just been released. Robert Wayne’s team at UCLA has been working on wolf genomes. Last year, UCLA researchers found that the Middle Eastern wolf populations were a greater source for diversity in domestic dog genes than any other wolf population– which suggested that dogs were first domesticated in the Middle East. This finding very strongly contradicted a comparison of many, many dog and wolf mtDNA sequences by Peter Savolainen of the Royal Institute of Technology at Stockholm, Sweden, which found that dogs were first domesticated in East Asia. Greater diversity of lineages was found in that region, and it is accepted that one generally finds more diversity in mtDNA lineages at the point of origin. (This is how we figured out that modern humans first evolved in East Africa).
The UCLA study that contradicted Savolainen’s findings used a very sophisticated analysis technique to compare different parts of the genome. Using what are called SNP chips (“snip chips”) researchers are able to look at many different parts of the genome rather easily. This study used 48,000 different SNP chips, which is actually a far more in depth analysis than comparing the diversity of mtDNA lineages to determine heritage. Mitochondrial DNA is inherited only through the mother, and although it is quite resistant to mutation, using it for analysis does have its limitation. Wayne’s original studies on the red wolf used only mtDNA sequences, which is one reason why the microsatellite data could still suggest that red wolves were an ancient North American species.
Well, on May 12, UCLA released the findings of a similar genome-wide study on wolves from Eurasia and North America, red wolves, coyotes and domestic dogs. It used roughly 48,000 SNP chips to examine 48,000 loci in the genomes of these creatures.
This is where red wolves fit:
Red wolves are genetically coyotes. Like many populations of coyote, these coyotes do have some wolf ancestry. In fact, many coyotes have both wolf and dog ancestry, with only the Western population remaining “pure.”
This study also found that coyotes likely lived in the Eastern parts of North America at varying times. There are wolves with definite coyote mtDNA that predate Columbus that have been found in places like New York and Quebec. Indeed, the researchers final conclusion is that there was a massive “hybrid zone” between wolves and coyotes in North America– the largest hybrid zone ever documented in a terrestrial vertebrate species. For millennia, wolves and coyotes have exchanged genes– as have dogs and wolves and dogs and coyotes.
The Great Lakes wolves, which were said to be the same species as the red wolf, were found to have quite a bit of coyote ancestry, but it was nowhere near as much as the red wolf. The Algonquin wolf was about 40 percent coyote, which was the highest concentration coyote ancestry in the Great Lakes wolf population, while the red wolf was 75-80 percent coyote and only 25-20 percent wolf. That is just a bit higher wolf ancestry than many coyote populations. One might actually call the Algonquin wolf a “stable hybrid,” but it may have coyote ancestry that traces back before Columbus. Which means it is a subspecies of Canis lupus with coyote ancestry with a unique ecological niche– which means that one could argue for its continued preservation.
Not so with with the red wolf.
This study strongly suggests that the red wolf is not a distinct species at all. In fact, it’s probably not even a member of a species that is endangered anywhere.
That finding is not going to go over very well at all. I have noticed that this study has not been widely publicized in the media.
I think it is possible that there was a southeastern wolf population that was closely related to the Great Lakes wolf subspecies. This animal became extinct and was absorbed into the growing coyote population. Perhaps this southeastern wolf already had some coyote ancestry from many generations before, but as it disappeared, it was forced to mate with coyotes to survive. It exists now only as that 20-25% heritage that is in so-called “red wolf.”
It is very likely that the red wolf as it exists now simply came from a population admixed coyotes with wolf ancestry in Texas and Louisiana. Some of these mixed coyotes retained some wolf features. These coyotes with wolf features were the ones that were trapped, deemed an endangered species, and then were released into Eastern North Carolina, where the US Fish and Wildlife service has tried to keep this breed pure under the assumption that it is a species of rare wolf from an ancient North American lineage.
As for the pack hunting aspect of this “red wolf,” coyotes can learn to form packs and evolve larger size, even if they have only traces of wolf ancestry. That is certainly the case with the Eastern coyote, which is now evolving into a kind of wolf-coyote that hunts deer. And that would explain why red wolves would form packs and hunt deer and raccoons in North Carolina. Pack-hunting is not exclusively the purview of wolves. Coyotes can do it, too.
This study is the most advanced analysis of the red wolf’s genetics that has yet been performed. These results have not trickled down into the popular conscience yet.
But once they do, it is going to be very hard to argue for the continued preservation of the red wolf in Eastern North Carolina or anywhere else it has been released. A big coyote with wolf ancestry that hunts deer is not an endangered species at all. We have them in West Virginia, but no one would call them an endangered species or some ancient wolf lineage. People want bounties on that coyote here.
But the US Fish and Wildlife Service and many, many scientists have put countless hours into red wolf. Lots of money has been spent.
How are these new facts going to be received?
It is no longer the red wolf. It is the creature formerly known as the red wolf.
That finding is an affront to the conscience of so many people.
And I don’t know how we can justify preserving this form of deer-hunting coyote when we already have another much more healthy population of deer-hunting coyote that continues to establish itself in the East.
These questions have yet to be answered.
But the debate surely will start soon. The US federal government is looking for programs to cut, and funding for red wolf reintroduction and management looks like its been dealt a pretty crushing blow.
I don’t see any how any other genetic studies can cast doubt onto what UCLA’s researchers have found.
There are plenty of other more worthy endangered species– including the Mexican wolf subspecies and the Island fox– that need some attention. Perhaps these animals could benefit from some of the funding and man-hours that have been allocated to red wolves.
That is one positive for which we can all hope.
The truth is not going to be received, but at least it’s the truth.
The study in question
Some more Retrieverman posts on the red wolf
|Red Dog||Jun 27 2012, 04:17 AM Post #2|
Many researchers disagree with Wayne, et al.'s conclusion the red/eastern wolf if a hybrid. Several methodological issues exist. For example, most samples came from Great Lakes wolves, which are mostly gray and eastern or red wolf hybrids. As a result, these wolves will not show up as red or eastern wolves in genetic testing. Closest thing to pure eastern/red wolf in northern regions come from Algonquin Park and only 2 specimens were sampled. Even so, these two Algonquin specimens grouped separate from other wolves and coyotes in Principal Component Analysis from Wayne et al's paper.
Most importantly wild coyotes and gray wolves in western North America do not hybridize. Therefore, it is hard to believe Wayne et al's theory that gray wolves and western coyotes (gray wolves are about 3-4 times heavier) hybridized frequently enough to form the red/eastern wolf.
Western coyotes and eastern/red wolves hybridize due to closer genetic history and relatively small size differential. Similarly, gray wolves hybridize with eastern wolves due to relatively small size differential.
Here are some of the researcher's views on this research.
From: Ron Nowak <email@example.com>
To: Meril, Rick
Sent: Sun May 22 11:24:25 2011
Subject: Re: new canid genetics paper
Rick---it's just more of the same; the paper is filled with qustionable material and conclusions. And as long as there is another major team of geneticists taking a diametrically opposite view, I cannot accept the validity of that whole approach---Ron
From: Bradley White <firstname.lastname@example.org>
To: Meril, Rick
Sent: Sun May 22 14:27:52 2011
Subject: RE: Fwd: FW: new canid genetics paper
We still interpret the data such that the eastern/red wolf are distinct but closely related species to the western coyote. Wayne et al are still making interpretations about coyote /gray wolf hybridization to support the original Wayne suggestion that the red wolf was formed a hybrid.
The Biology is clear; coyotes and gray wolves do not hybridise. The gray/eastern hybrids do not hybridize with either eastern or western coyotes. Coy wolves or eastern coyotes have little to no gray wolf material.
From: Patterson, Brent (MNR) <email@example.com>
To: Meril, Rick
Sent: Wed May 25 12:13:46 2011
Subject: RE: Fwd: FW: new canid genetics paper
Tyler, Linda & I first heard Roland present these results at the Midwest wolf Stewards meeting in Wisconsin about a month ago and were certainly both interested and intrigued. While we remain open to rigorous testing of the ideas suggested by this work re the origins and taxonomy of eastern wolves (C. lycaon), we are not yet convinced and have concerns that impact the conclusions of vonHoldt et al. concerning the eastern wolf.
One of our primary concerns is that the authors refer to eastern wolves and Great Lakes wolves interchangeably, and conduct their subsequent analyses based on this assumption. We must assume some of the blame for this confusion given suggestions in earlier works from this lab of a broad range for eastern wolves (e.g. Grewal et al. 2004; J. Mammalogy 85: 625-632), but in recent papers (e.g. Rutledge et al. 2010: Heredity 105: 520-531; Wheeldon et al. 2010: Molecular Ecology 19: 4428-4440) we tried to clarify that: 1) while there are likely no remaining unhybridized eastern wolves in the wild, the closest living relatives to the historic eastern wolf live in and immediately around Algonquin park in central Ontario. These wolves are distinct from wolves in NE and NW Ontario, as well the Great Lakes States, and 2) Although wolves in the Great Lakes States and much of Ontario and Quebec contain some eastern wolf genetic material, they are not eastern wolves and both phenotypically and genetically (based on autosomal microsatellites) group more closely with Gray wolves, C. lupus than with C. lycaon (again, as typified by wolves in Algonquin). Given this, the finding that Great Lakes wolves and Red wolves did not share a common evolutionary origin is not surprising. We have suggested a common origin for Red wolves and Eastern wolves (again typified by, and largely restricted to wolves in Algonquin), NOT between Red wolves and the Great Lakes wolf which, as mentioned above, is a hybrid of C. lupus and C. lycaon.
Given that VonHoldt et al. only analyzed DNA from 2 Algonquin wolves, and that we don't know when and exactly where these samples were collected (i.e. they could have been coyotes or hybrids collected somewhere in or around Algonquin), we don't believe that the hypothesis of eastern wolves as a distinct North American evolved species was adequately assessed by this work. Note also that the Wilson et al. (2000) canid evolutionary model (CJZ 78: 2156-2166) of the eastern wolf suggests divergence from the western coyote only 150-300K years ago. This time is barely sufficient to see differences in the mtDNA control region resulting from mutation, so the finding that genomic SNPs did not differentiate eastern wolves from western coyotes is not surprising. Another concern relates to the analyses conducted using the program Structure. Anyone familiar with this program, used to assign membership to different genetic groups, knows that it would be highly unlikely for any "population" consisting of only 2 individuals to separate as a distinct group from other larger populations. Nonetheless, it is interesting that the PCA conducted by VonHoldt et al. (see their Fig . 3) places the 2 Algonquin samples separate from all other groups although the authors arbitrarily grouped them with Great Lakes wolves.
Future research might yet reveal that there never was a North American evolved Red wolf or Eastern wolf, and that these animals are indeed merely hybrids between C. lupus and C. latrans, but if so we wonder how the following lines of evidence supporting a North American evolved wolf distinct from the Gray wolf will be rectified:
1) Hybridization between eastern wolves/ red wolves and coyotes is pervasive where they are sympatric in eastern North America but hybridization between wolves and coyotes remains exceedingly rare or absent in the west. Hybridization between wolves and coyotes is also very rare across the Western Great Lakes region (see Wheeldon et al. paper cited above), and in northern Ontario (east and west). The range of ratios of abundance of wolves: coyotes vary widely in both eastern and western North America so saying the 2 species only hybridized in the east because of skewed species ratios requires quite a leap of faith.
2) How does one explain the presence of mitochondrial haplotypes C3 and C13 (see Rutledge and Wheeldon refs cited above); both of which are common in eastern wolves and their associated hybrids, but neither of which are found in non-hybridizing wolves or coyotes (i.e. gray wolves and western coyotes).
3) Evidence of a separate Y-chromosome eastern wolf lineage (Wilson et al., manuscript in review).
In summary, while we agree that the approaches employed by VonHoldt et al. represent an important step forward re analysis of canid taxonomy; until a more representative and balanced sample containing eastern wolves (i.e. Algonquin wolves), historic pre-Columbian eastern wolf samples, and the appropriate out groups, is similarly analyzed we consider the hypothesis of a North American evolved wolf independent of the gray wolf still viable.
Research Scientist – wolves and deer
Adjunct Professor, Trent University, Environmental and Life Sciences Graduate Program
President, Ontario Chapter of The Wildlife Society
Ontario Ministry of Natural Resources
Wildlife Research and Development Section
Trent University, DNA Building
2140 East Bank Drive
K9J 7B8, CANADA
Tel: (705) 755-1553
Fax: (705) 755-1559
Edited by Red Dog, Jun 27 2012, 04:23 AM.
|Taipan||Jun 27 2012, 08:17 PM Post #3|
|Can you guys stick a copy of the above in the Red Wolf Carnivora profile? Thanks.|
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