New species of black-backed jackal indicated through mitochondrial DNA analysis

cape vs east african

Cape jackal  (L) and East African black-backed jackal (R)

The molecular revolution in biology has caused a great deal of turmoil in the taxonomy of Canids. Long-time readers know that full-genome comparisons have recently found that the red wolf and Eastern wolf are hybrid between coyotes and wolves, and one implication of the recent origins of the coyote is that the coyote itself might be better classified as a subspecies of wolf. 

Mitochondrial DNA comparisons, though potentially erroneous in determining the exact time of divergence between species or subspecies, have also revealed that the “golden jackals” of Africa are much more closely related to wolves than Eurasian golden jackals.  Classifying African golden jackals is going to take more analysis of their genome, but they are either a species on their own or a subspecies of wolf. They have evolved in parallel with both the Eurasian golden jackal and the coyote.

We also know now that the red fox of the Old World is quite divergent from that of North America, enough that some authorities are reviving the old Vulpes fulva for the North American species.  Red foxes in the Eastern and Midwestern US are actually part of this endemic North American species and are not, as the folklore claimed, to be derived from seventeenth and eighteenth century introductions from England.

Recent mitochondrial DNA analysis also revealed that Eastern and Western gray foxes are perhaps separated by 500,000 years of evolution. 

So we’ve likely lost two wolf species in North America. The coyote’s validity is questionable. But we’ve gained either a wolf species or subspecies in Africa.  We have also potentially gained two species of fox in North America.

With all of these new findings in DNA studies, scientists are looking more and more closely at other long-established species.

Last week,  a study of the cytochrome b gene of black-backed and side-striped jackals revealed that these jackals, too, have some secrets.  Cytochrome b genes are part of the mitochondrial genome.

At one time these animals were considered part of Canis, but the current trend is to classify them in their own genus (Lupulella).* They are quite divergent from the rest of the wolf-like canids, much more so than dholes and African wild dogs are. If dholes and African wild dogs are in their own genera, then it makes sense that these two jackals should have their own genus name.

But if they are that divergent from the rest of Canis, then it’s very possible that there are other secrets, and this limited mtDNA study certainly raises some important questions.

The researchers found that the Cape subspecies and East African subspecies of the black-backed jackal (Lupulella mesomelas) actually diverged 2.5 million years ago.

I’ve always thought that there was a possibility of these two jackals being distinct species. The East African black-backed jackal has a shorter muzzle, comparatively larger ears, and usually lack the dense coat of the Cape jackal. The Cape jackal reminds me very much of Southwestern forms of coyote, with longer muzzle and thicker fur. What’s more is that the Cape jackal comes in a white and a golden phase that are not seen in the East African black-back.

If this deep divergence is confirmed in the full-genome or simple nuclear DNA studies that are very likely to be performed, then we likely have two species of what are called black-backed jackals now.

The researchers also found through this same analysis that the West African side-striped jackal diverged from the other two populations 1.4 million years ago, which certainly would raise some questions about its species status as well.

Again, we’re going to have to wait until full-genome analyses are performed, but I’ve always suspected that there are more than two species of endemic African jackal possessed some cryptic species.  I also have suspected that both side-striped jackals and black-backed jackals have hybridized a bit. This speculation could be revealed through the same full-genome or nuclear DNA studies that could examine the taxonomy within these supposed species.

Finally, the distribution of black-backed jackals is disjointed. The East African and Cape variants are separated by 800 miles. Several other small carnivorans have a similar distribution. The bat-eared fox and the aardwolf have disjointed distributions in which one population is in East Africa and the other in Southern Africa. It is very possible that similar deep genetic divergence exists within these species as well.

These potential cryptic species are worth investigating, and they certain put some of these “red wolf” controversies with in proper perspective.  If that 2.5 million-year divergence is upheld within the black-backed jackal populations, it really does become hard to justify the red wolf.  It is descended from two putative “species” that really aren’t that divergent at all by comparison.

 

 

 

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*A bit errata:  I initially called the new scientific name of the side-striped jackal Lupulela adustus, which is just a modification of Canis adustus.  Most of the literature I’m corrects the gender to Lupulella adusta.


Natural History

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