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Posts Tagged ‘Lupullela’

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.

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lupullela adustus

Lupullela adusta, new name for the side-striped jackal. 

As we have examined the genomes of various  dog species, one problem has become evident:   The genus Canis is paraphyletic. Two endemic African jackals, the side-striped and black-backed jackal, are actually more distantly related to the wolf-like canids than the African wild dog and dhole are.

One way to solve this problem would be to make the dhole and African wild dog part of Canis, but the problem with this classification remedy is that the paleontology on the dhole and African wild dog is quite hard to trace and still fairly controversial. Anything in their lineage needs to have different classification in order to keep those specimens distinct from the main wolf-like canid clade.

The other solution is to give the black-backed and side-striped jackals their own genus.  In the early part of the twentieth century, it was common to refer to these species within a genus called Lupullela. I’ve noticed that a few papers have popped up using this genus, like this one that examines which predatory species may have left the remains of quarry in a Late Pleistocene cave in Morocco.

I don’t think it will be very long before both the side-striped and black-backed jackal will be commonly referred to as Lupullela.

I won’t be complaining. Paraphyly is something I find annoying.  We are classifying nature in light of evolution, and making sure we have true clades in which animals are classified according to their common descent is important.

The classification of jackals is undergoing a sea change. The creature known as the golden jackal is two species, but the exact way to classify the two species is still hotly contested.  The African “golden jackal” is closer to the wolf and coyote than the Eurasian “golden jackal,” but we don’t have good full-genome data to place the African golden jackal properly. It could wind up that the African golden jackal is very close to the wolf, as the coyote was recently found to be, and this will make the actual classification really touchy.

But that current debate is nothing compared to the way we are starting to classify the two divergent jackals of Africa. These animals don’t get studied as much, but I would highly suspect that there are surprises hidden in their genomes. It could be that there are actually several species currently classified as black-backed and side-striped jackals, and it is also highly likely that there are hybrids among these forms as well as between the species classified currently as side-striped and black-backed jackals.

Neither jackal is endangered, but they are something different, something that is at least worthy of study.

These are sort of forgotten dogs, and their secrets are only now just coming to light.

 

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