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Archive for the ‘Carnivorans’ Category

giant panda

Giant pandas are the last survivors of their entire lineage of bears.  The Ailuropodinae were once a diverse, mostly omnivorous lineage of bears that were widespread throughout Eurasia and North America during the Miocene.  About 2 million years ago, one extant line of these bears began to adapt to more herbivorous diet, and we believed that this shift to a more herbivorous diet was directly analogous to becoming a bamboo specialist.

The truth is no one ever looked at the carbon isotopes in ancient and modern panda remains to see exactly what when giant pandas became bamboo specialists. Well, a study just published in Current Biology has revealed something quite shocking.

The authors did look at the isotopes in several ancient pandas, including the modern species, but what they found was that the shift to a more vegetarian diet was probably accomplished by the Pliocene.

However, the bamboo specialization did not become established in modern pandas until between 5,000 to 6,000 years ago, roughly about the same time as the rise of the Indus Valley Civilization and the Ubaid Period of Mesopotamia.

This finding has some interesting implications. One is that specialization can happen relatively rapidly in the evolution of mammals.

The other is that specialization can be quite disastrous for a species. Evolution has no grand design, and if there were some kind of foresight in the whole enterprise. giant pandas would have been better of living generalist herbivores.

It is also not really clear what pushed giant pandas into this specialization. Maybe there was a massive range expansion of ungulate herbivores into their forests that pushed them towards that diet.  Maybe there were some human-related factors that led to this specialization.

The truth is we don’t know.

I do, however, have a big question:  Did the Qinling panda evolve the bamboo-specialist diet at the same time as other giant pandas?

The reason I ask is that full genome comparisons revealed that Qinling panda diverged from the other giant pandas 300,000 years ago?

That means that these two forms of giant panda split from each other long before this bamboo specialization. It seems to me that they would evolved this bamboo specialization independently of each other.

There are also fewer studies on Qinling pandas. There aren’t as many studies on this form of panda, and it might not be as bamboo-specialized as the most common form.

Very real conservation implications could come from this discovery.  This discovery means that we should be looking more carefully at the Qinling panda in the wild to see if its diet really is different. This study included only modern pandas from Sichuan, so it would be quite interesting to see what wild Qinling pandas isotopes are like.

So, yes, this is an amazing find, but it has very real implications for panda conservation. It could potentially add more evidence for the Qinling panda as a distinct (and thus very endangered) species if it is found that Qinling pandas have a more diverse diet.

And if they have the same diet, then this diet evolved in parallel between the common giant panda subspecies and the Qinling panda.

Which is pretty amazing that both extant forms of panda bet on this same limited niche.  And this is an odd fate for what were once wildly successful omnivorous bears across the Northern Hemisphere.

Evolution takes us on weird journeys, doesn’t it?

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clive being playful

So when we had Clive out today he urinated a few times outdoors, including up against a tree trunk of one the silver maples in front of the house.

I made dinner this evening, and we had a boarding client who was coming to pick up her dog. Jenna took the client dog out for one last good walk about an hour after the sun set.

She came running back in the house telling me that she could smell red fox urine very strongly, and after careful examination, we noticed red fox tracks coming from across the road into our front lawn.

Clive is never taken near the road. He attracts too much unwanted attention, and our local conservation officer doesn’t like getting calls about a fox he knows is perfectly permitted and licensed.  Plus, Clive could get spooked and pull his leash loose, and he would probably run into the road and be hit by a car.

So what happened was that a dog fox in the neighborhood caught wind of Clive’s markings around the silver maples.  Last summer, I smelled where a red fox had urinated on one of these trees, as did every single one of our dogs, so I knew they were in the area. But now that we have a tame young male fox, the local breeding male fox is less than impressed with the young upstart leaving those markings on turf.

Clive is attracting the attention of the neighbors. My guess is we’re going to see lots more of their sign and maybe catch a glimpse of them as the late winter red fox mating season winds up.

I doubt that any of the local reds are cross foxes. All the ones I’ve seen in Ohio, West Virginia, and Pennsylvania have been the normal phase reds. But the foxes don’t know what color they are. They just operate by their nose and their base instincts.

Clive can never go wild. He’s from a long line of fur farmed foxes, and if he were to be released, he’s so friendly with people that he’d probably be suspected of being rabid and killed on sight.

So here is another aspect of owning a tame fox. The local red foxes don’t really care that much for the tame ones, and virtually everyone in the continental US lives near red foxes. If you bring a tame one into your home, you will be upsetting the locals, and I don’t just mean your human neighbors either.

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canada lynx

North America has two species of lynx, the widespread bobcat (Lynx rufus) and the boreal-adapted Canada lynx (Lynx canadensis). The two species do have some range overlap across the northern-tier of states, and when Canada lynx ranged down the Appalachians, their range overlapped much more extensively.

These two animals behave quite differently from each other. The bobcat is a generalist predator that hunts everything from mice and voles up to white-tailed deer, while the Canada lynx specializes in hunting snowshoe hares.

The bobcat is found in Mexico and throughout the southeast, especially in Florida.  Those southernmost bobcats are often not much larger than domestic cats, but the biggest bobcats, which are found in the Great Lakes states, are actually larger than Canada lynx.

It is well-known that bobcats and Canada lynx do hybridize. Hybrids have been produced in captivity, and hybrids have been encountered in Maine, New Brunswick, and Minnesota.  These hybrids are apparently fully fertile, which leads to the question of how much the two species really do hybridize.

A group of researchers looked into a big sample of bobcats and Canada lynx that came from across the continent. Of the 2,851 cats sampled, only 7 had any evidence of introgression from one species to the other.

This finding shows that bobcats and Canada lynx do hybridize, but it is virtually unknown in the wild. The authors caution that if Canada lynx numbers ever become low, bobcat introgression could swamp the genetics of that population, effectively making the species disappear through hybridization.

This finding is quite different from what has been discovered with gray wolves and coyotes. Gray wolves and coyotes have apparently exchanged genes across North America, and animals of mixed coyote and gray wolf genetics are pretty common.

Because we don’t have evidence of a hybrid swarm, which we do with wolves and coyotes, we have very good evidence to consider bobcats and Canada lynx quite distinct species.  And conversely, it is within reason to question the validity of coyotes and gray wolves as being distinct species

I would love to see a similar study to the genome comparisons performed on gray wolves, coyotes, and admixed canid populations in North america performed on Canada lynx and bobcats. My guess is that there will be some evidence of very limited hybridization between the two species, but it will not be like coyotes and gray wolves.

We don’t have a good handle on when bobcats and Canada lynx last shared a common ancestor. We need some more genomic data to make this claim, but what we know now is that Canada lynx and modern Eurasian and Iberian lynx are sister taxa.

The bobcat is thought to be more basal to the lineage.  Lynx species have been roaming North America since the Pliocene. Indeed, the earliest lynx fossils were found in North America, not Africa, as we previously believed.

The bobcat evolved in North America. It is the last survivor of the endemic North American lynx that gave rise to the other species in Eurasia, while the Canada lynx came back from that ancestral Eurasian lynx population some 200,000 years ago. 

These animals have likely been distinct from each other for a very long time, but they have not yet lost chemical interfertility. It will likely be a while before this happens, but if climate change continues to threat Canada lynx populations, the bobcat will move north into their range and hybridization could become a threat.

So stay tuned to see what happens, but the genetic data clearly show that bobcats and Canada lynx are two distinct species that do rarely hybridize.

 

 

 

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sea mink

Depending upon how one understands the red wolf, the United States has had only two native carnivoran species go extinct. One of these was the Caribbean monk seal, which was one of three species of monk seal that once swam the warmer waters of Hawaii, the Mediterranean, and Florida, the Gulf of Mexico, and the West Indies.  The Mediterranean monk seal still holds on, and I’ve laid eyes upon a few Hawaiian monk seals. But the Caribbean species is gone. Sightings still persist in redoubts throughout the West Indies, but virtually every expert believes the Caribbean monk seal to be extinct.

The second species we lost is a bit of a mystery, and yes, there is a bit of a debate as to whether it really was a species at all. The North American mink is a fur trade staple. It has been bred in captivity almost as extensively as red foxes have, and it has been accidentally introduced on more than a few occasions.

In its native range, it is quite widespread, and studies of North American mink and their predation upon muskrats were the basis of early predator-prey ecological studies.  These animals are even undergoing a sort of domestication and training as hunting animal in Utah.

But that common species of North American mink may have not been the only one on this continent. Another mink species was described along the rocky coasts of Maine and the Maritimes.  It was called the sea mink, and unfortunately, it was not described until 1903, when it was already extinct.  The trappers of Maine and the Maritimes knew the mink of the coast was somewhat different, but they had already trapped it out by 1894. The animals were described as being very large mink, measuring 36 inches in length and possessing a reddish coat.

When they were eventually described as a distinct species in 1903, much of the data backing their taxonomic status was based upon skulls taken from shell middens of the Native Americans. Their dentition was different enough for some scholars to maintain that this mink with the big teeth was indeed its own species. The current consensus is that there was a sea mink, and this consensus is made upon an another more sophisticated comparison of its dentition with other North American mink.

It should be noted that not everyone agrees with this species status based upon dentition alone. Richard Manville has long maintained that the sea mink was a unique subspecies of North American mink. Manville examined several specimens, including one that he thought was intergrade between the sea and “wood” mink form, and he concluded that the sea mink was nothing more than a subspecies.  Manville noted that purported sea mink remains dating to around 4,000 years ago were found in inland Massachusetts, well south of where the sea mink was supposed to range. Further, they were found so far from salt water, which led Manville to question whether the sea mink was so regionally distributed and so connected to the ocean as was believed.

Many comparisons have been made between the sea mink and the North American mink that live on the Alexander Archipelago of Alaska. Those contemporary mink are quite large and live very similar lives. Like the sea mink, this large Alaskan mink relies upon cold, boisterous seas for its food. Shellfish feature also prominently in its diet, and it could be argued that the two forms evolved in parallel of each other.

I am leery of modern species being described solely off of morphological characters alone. Because sea mink remains definitely do exist that could be used for DNA extraction, one wonders why no one has tried to use this method to resolve this question.

Now that this large mink is now extinct, its taxonomy is less urgent.  This larger-sized sea mink was in demand because of its coarse fur, which would have been in demand to make fur coats, and its larger size meant that fewer mink would have to be trapped to make the same size of garment. It was definitely trapped out of its range, and all that was left was that other form of mink, which the New England trappers called the “wood mink.”

If this sea mink was just a subspecies, it likely exchanged genes with the local wood mink, and there is a distinct possibility that we could find its genes in some “wood mink” living today.  Even if it were a distinct species, it is possible that the two forms didn’t lose chemical interfertility.

So maybe the US lost two species of carnivoran in historic times. Or may we’ve lost only one. Just like the species status of the red wolf, the sea mink is still contentious in the literature, but unlike the red wolf, there are no molecular studies that have attempted to resolve this problem.

And we are left wondering about the mystery of what has passed, once again.

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Snow leopards are those high altitude cats that have long fascinated Westerners. Peter Matthiessen won a national book award for writing a memoir about his trip to the Himalayas to go looking for one, and for most of my life, we had no idea how many were around or where their exact range was. Huge debates about their taxonomy weren’t even resolved until recently, when it was finally settled that they were indeed members of the genus Panthera and that they were a sister species to the tiger.

But as we’ve looked at the snow leopard genome, something really odd has come to the fore. In the bulk of their genome, they are clearly closely related to the tiger, but their x-chromosome and mitochondrial DNA are oddly quite close to those of lions.

In 2016, genome comparisons were performed for many cat species, and the researchers found that these lion-like x-chromosomes and mitochondrial DNA entered into the snow leopard population just before the lion and leopard split. The authors think that there was an introgression between the ancestral male snow leopard and female lion/leopard ancestor. This matriline is now all that survives in snow leopards.

So yes, snow leopards are most closely related to tigers, but they did receive some genetic contribution from the lion and leopard ancestor. This hybridization happened over two million years ago, but it is the closest thing to a liger ever occurring in the wild.

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This is the same story that John Vaillant recounts in The Tiger, but this documentary plays up the role of Trush’s laika a lot more. Warning: lots of gory images in this film, including human remains.

This is my all-time favorite wildlife story. It’s like Jaws met No Country for Old Men, and it’s a true story!

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River otters are pretty bad-ass.

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