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Archive for the ‘wildlife’ Category

black squrrel

As long-time readers of this blog know, the black coloration seen in North America and Italian wolves and in coyotes originated in domestic dogs. Indeed, the black coloration in North American wolves originated from a single introgression of a black domestic dog in the Northwest Territories or the Yukon between 1,598 and 7,248 years ago.  Of course, we now know that there is significant gene flow between dogs and certain populations of gray wolf and that this gene flow has been going on for some time.

I have often wondered about color genetics and gene flow between species. One species that is particularly beguiling for speculation for me was always the origin of melanism in Eastern gray squirrels. Melanistic Eastern gray squirrels are more common in Ontario, Quebec, and Michigan, but there are isolated populations south of these locations.

A new paper just published in BMC Biology revealed that melanism in Eastern gray squirrels most likely had its origins from hybridization with the fox squirrel.

Melanism has evolved twice in fox squirrels. The melanistic ones in the Southeast have a mutation called ASIP A3.  Melanistic Western fox squirrels have a mutation that causes a deletion in the MC1R. This allele is called MC1R∆24.

What is interesting is that melanistic Eastern gray squirrel have the same mutation.

The authors contend that the most likely explanation for this shared mutation is hybridization between fox and Eastern gray squirrels, although ancestral polymorphisms and earlier hybridization between gray squirrels and fox squirrels cannot be ruled out as possible origins either. However, The authors think it originated in fox squirrels because it resembles other fox squirrel MC1R haplotypes.

This finding is pretty interesting because I live where both species are common, and I use to live where there were lots of black gray squirrels.  I had read accounts of fox squirrels mating with gray ones, but the accounts I read said that no offspring resulted from the mating.

I assumed that the two species could not hybridize, and I still have not seen any literature that even suggests hybridization could occur until I read this paper.

More work is going to be needed to see exactly how this mutation originated and if there are other traits that originated in one species that now are found in the other.

And yes, there is that old wives’ tail that says that gray squirrels castrate fox squirrels to reduce the competition. What actually happens is that when squirrels are hunted in the early part of the season, the testicles shrink in size, so that they appear to have been castrated.

But I have never heard of these two species hybridizing. Indeed, it may be that the hybridization that transferred that particular mutation onto Eastern gray squirrels happened far back in the evolutionary history of both species, when they were still chemically interfertile.

However, they might still be able to hybridize. It is just that no one has ever documented a true hybrid between the two species.

But I am certainly open to the possibility.

So it is likely that black gray squirrels resulted from introgression, just as black wolves and coyotes do.

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narwhal hybrid.png

a: beluga skull b. “narluga hybrid” c. male narwhal skull.

In the 1980s, an Inuit subsistence hunter in Greenland killed three gray whales that looked suspiciously like belugas at first. However, they were oddly gray. The fins resembled a beluga’s, while the tail looked like that of a narwhal.

The hunter kept one of the skulls, eventually donating it to science, where became the property of the Greenland Fisheries Research Institute. A scientist working for that institute, Mads Peter Heide-Jørgensen,hypothesized that this skull came from a hybrid between a narwhal and a beluga.

It was only today that a study was released in the journal Nature that revealed that this whale was indeed a hybrid. The DNA analysis revealed that male beluga mated with a female narwhal to produce the creature.

The skull was quite strange. Belugas have 40 homodont teeth. Narwhals are toothless, except males. The males have one really long canine tooth that sticks out as a tusk. Sometimes, they have two, but most have only one true tooth. It is spiraled like what is expected form the mythical unicorn. They do have only a few vestigial teeth.

The hybrid had 18 teeth, many of which were pointed out horizontally and spiraled like the vestigial teeth of the narwhal.

Isotopic analysis also revealed that the hybrid had a different diet from either parent species, both of which catch fish or squid in the open water. The beluga hunts fish at depths of up to 500 meters, while the narwhal hunts fish or squid at depths exceeding 800 meters. The isotopic analysis revealed that the narluga was eating mostly benthic prey, which means it was eating mostly shellfish from the sea floor.

So this study raises so many questions. Analysis of the narwhal genome revealed that gene flow between the two species stopped between 1.25 and 1.65 million years ago. The initial split happened around 4 million years ago, and that study thought that an viable hybrids would be unable to reproduce. However, the authors of the study cautioned that a larger sample size of individual narwhal and beluga genomes from across their range might reveal more recent dates on when gene flow stopped (if it did at all).

So it is not entirely clear that this hybrid would have been sterile, but we also have no further evidence of hybrids anywhere else.  It is quite possible that these hybrids could be fertile, and if they are, climate change could cause the eventual genetic extinction of the narwhal.

The morphology and feeding behavior this odd whale might point to the origins of the narwhal. Perhaps the ancestral narwhal was a benthic feeding whale that later lost its teeth to become a whale that hunts squid and fish at great depths with an almost toothless mouth.

Having teeth like the hybrid is a great adaptation for this particular diet, because the forward pointing teeth can poke around and dislodge shellfish more easily.

If these hybrids are fertile, then one could see the eventual development of a hybrid whale species that has its own niche as a benthic feeder in the arctic.

It is an amazing find, and chances are there will be more discovered. Further, as scientists examine genomes from belugas and narwhals from a wide geographic distribution, we might see evidence of some hybridization.

Hybridization could also increase genetic diversity in narwhals, but if these hybrids must eat a fundamentally different diet than narwhals do, it might become difficult for these hybrids to add their genes to narwhal populations. They just cannot hang out for extensive periods of time, before they have to split off and engage in divergent feeding behavior.

So this discovery does generate lots of speculation and raises several important questions that need to be addressed.

Pretty cool.

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lined seahorse

Seahorse always fascinated me. When I was a kid, we’d go to the souvenir shops at the beach in North Carolina, and of course, there would be many shells and sand dollars to buy. And you could pick up a dried-out seahorse. The racks would be full of dried out seahorses, hundreds and hundreds of them.

I never really thought about seahorses as being potentially threatened by anything. My child brain could not fathom how much trouble they could be facing.  But even those species that live off the coast of the United States and Canada are under threat from pollution and over-development. They are also in demand for Chinese traditional medicine, and with the Chinese economy growing as rapidly as it has for the past few decades, this demand has only increased the pressure for both species.

Two species found in the Western Atlantic are the lined seahorse (Hippocampus erectus) and the longsnout or slender sea horse (H. reidi).  The lined sea horse has a more northerly distribution than the longsnout, but their ranges do overlap from North Carolina to Venezuela. The two species do not readily hybridize in the wild, though they certainly have done so in captivity.

With the lined sea horse being listed as “vulnerable” by the IUCN and the longsnout as “near threatened,” there are real conservation concerns for both species, and they are indeed being bred in captivity now with hopes of giving a boost to the dwindling wild populations.

However, these two species are often housed together in aquarium and zoos, and they have interbred.  A recent paper in the Journal for Zoo and Aquarium Research has identified a simple molecular technique for identifying hybrids in captive populations, but the paper also notes the possible issues with hybrids.

The obvious problem is that conservation plans for restoring species are designed to restore a particular species, not hybrids between the two. Yes, this is the big boondoggle behind conserving species that hybrid with another, but it is one thing to have hybrids readily occurring in the wild. And it is quite another if hybrids largely exist because of aquarium practices.

So the authors urge zoos and aquariums to stop putting these two species together and to work much harder at maintaining “purebred” populations of each species.

However, the authors point out that the hybrids could be useful for conservation in another way. With improved seahorse husbandry techniques, various farms could potentially breed populations of hybrid seahorses and fill the needs of the growing Chinese market.

These two species may have split from their common ancestor over 14 million years ago, but hybrids between fish species can happen between species that have been divergent for many millions of years.

Humanity’s effects upon the ocean have been greatly underestimated.  Much of what has happened to the ocean has been out of our sight for so long that we assumed that all was fine.

But future for many species of seahorse is not secure at all, and if we are to be proactive and work on restoring diminishing stocks of various species, we must work on controlling potential problems that can come from hybridization in captivity.

So for conservation purposes, we must try to keep strains distinct for those that could be released into the wild, but for the Chinese medicine market, breed the mutts.
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This video was posted on an outdoor channel in Eastern Washington:

This guy is a good naturalist, and he has excellent trail camera placement.

But what he’s actually seeing are not hybrids. What he is seeing is the wonderful transition from the mule deer type that is common in the interior West to the black-tailed deer type, which is common more toward the Pacific Coast.

Those two deer are now recognized as a single species (Odocoileus hemionus), though the mule deer type is recognized to have some hybridization from the white-tailed because it possesses white-tail-like mitochondrial DNA.

Hybridization does occur between white-tails and mule deer, but the survival rate is quite low among the F1s. Mule deer have a stotting evasion behavior, which is incompatible with the white-tail’s bounding pattern. The offspring inherit both behaviors, and they cannot effectively evade predators.  The stotting behavior is used to communicate to a predator that might be hunting the mule deer on the open range that this deer awfully healthy and that it should try a different target. White-tailed deer are forest deer, and they just bound away from predators.

But apparently, there was an introgression of a white-tailed deer matriline into what became mule deer at the Pleistocene/Holocene boundary.

So this transition from true interior West mule deer to the Pacific blacktails apparently starts in Eastern Washington, and of course, you’re going to see the transition somewhere. These two forms interbreed because they are subspecies, and at some point, you’re going to hit the transtional zone between the two, where it gets hard to tell which is which.

 

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The 17-year-cicadas (Magicicada) are coming out this year in this part of Ohio, as well as the Northern Panhandle of WV and parts of Western PA.  They emerged last night on our lawn and began their adult form on our silver maples.

(All photos by Jenna Coleman).

magicicada 2019

The discarded exoskeleton of the Magicicada nymph:

magicicade nymph husk

An adult one is bursting through its nymph exoskeleton.

bursting throuhg the exoskeleton

The adult exoskeleton is pasty and takes a few hours to harden into black.

pasty exoskeleton magicicada

hardened into black

Our maples are covered with discarded nymph exoskeletons, drying adults, and adults that are almost ready to start whirring in the trees.

maples coavered

The adult form is so oddly ugly that it is beautiful.

magiicada

magicada 2

magicciada 3

These cicadas have a life-cycle based upon brood. They spend 17 years underground. When that time comes in late May, they climb up out of the ground and begin mating and laying eggs. Their will be whirring loudly from the trees in a couple of days, and by the end of June, you won’t see a single one. This reproductive strategy is meant to overwhelm their many predators with so many easy targets that more than a few will manage to reproduce.

This blog covered another Magicicada outbreak in 2017, but that was a different brood. This one is Brood VII. That one was Brood V. 

So we are ready for the weird noise of these cicadas as they complete their final life stage.

And we will soon be tired of it.

 

 

 

 

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Posted on The Atlantic’s Youtube channel, this week:

He’s one of my heroes. I won’t lie about it.

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woodland caribou

I had the pleasure of listening to Diane Boyd, a noted wolf expert, talk about wolf conservation issues on Steven Rinella’s Meatear Podcast. It is very good info about wolves, including wolf conspiracy theories.  One part I found particularly interesting was about the history of Isle Royale, which is experiencing a wolf reintroduction this year. Isle Royale is, of course, home to one of the longest running ecological studies that has examined predator and prey relationships.  The study mainly focuses on moose and wolves on the island, but an inbreeding depression reduced the wolf population of the island to two individuals last year.

I have always thought of Isle Royale as being a place of wolves and moose. But wolves came to the island only in the 1949, and moose came only in the early 1900s.

In the podcast with Diane Boyd, she mentions that Isle Royale was originally known for its woodland caribou and Canada lynx.  Boyd speculated that moose introduced brainworm to the caribou, but a more likely reason for their disappearance is that woodland caribou are sensitive to human-centered activities. All the logging and mining that happened on Isle Royale could not have done the caribou many favors. The last caribou was documented on the island in 1925.

Canada lynx are not particularly good predators of caribou. They were likely living on snowshoe hares, which are found on the island. Maybe, when snowshoe hares experienced the crash portion of their boom or bust population cycle, the lynx occasionally turned to hunting caribou, as they did in Newfoundland.

If Isle Royale’s fauna had remained the same at the beginning of the twentieth century as it did at the beginning, maybe it never would have become such a great place to study predator and prey population dynamics.

The restoration of wolves to Isle Royale, which is happening as I write this piece, is an attempt to bring back an ecology that dates all the way back to 1949. I have readers who can remember 1949.

We have this idea that conservation is about restoring things to an Eden when things were unmolested, untrammeled, and pure.  But what seems to be timeless is ultimately just temporary.

Last night, I was grappling with the concepts of conservation, specifically the idea of rewilding.  Rewilding is about restoring organisms to the land that were there at some point. Some think of feral horses in the West as being rewilded, from the Pleistocene though I am greatly skeptical of this idea.

Of late, though, there have been proposal to restore Pleistocene fauna to their former ranges, and if that animal can’t be found exactly, then a facsimile will be brought in.

In the case of North America, African elephants have been proposed as being equivalent of the Columbian and woolly mammoths. African lions might take the place of old Panthera atrox.   Some have even suggested that the plains of Texas, which are filling with blackbuck, might be a great place to turn out some cheetahs, thinking of course that Old World cheetahs are somehow the equivalent the long-legged coursing cougars that once roamed the Pleistocene wild of North America.

We don’t really know what killed off all these fantastic beasts of the Pleistocene. I lean more toward rapid warming at the time of the Pleistocene/Holocene boundary, but many reasonable people find some merit in Paul Martin’s “Overkill Hypothesis.”  This hypothesis contents that the Siberian hunter-gatherers who came into North America wound up killing off much of the megabeasts, or lacking such evidence of profligate killing, contend that these hunter-gatherers killed off a few keystone species, such as mammoths and mastodons, to cause ecosystems to collapse.

If this hypothesis is correct, there is a moral force for this Pleistocene rewilding concept. Humanity is responsible for killing off the megabeasts, and it is our duty to restore North America to its former glory as the land with the great bison, pachyderms, camels, and equines.

But this takes me back to Isle Royale. Humans certainly disrupted that ecosystem. If we wished to restore Isle Royale to its form ecosystem, we should be shooting off all the moose on the island and turning out woodland caribou from Ontario. We shouldn’t be trapping wolves and turning them loose. We should be trapping Canada lynx instead.

Canada lynx are much rarer in the Upper Midwest than gray wolves are, so by a triage of the conservation needs of the species, it would make more sense to preserve Isle Royale for the lynx.

Of course, that’s not what is being done. The wolf and moose studies are too deeply ingrained in our science and our understanding these two species. And if you were to twist my arm, I’d say choose wolves and moose over caribou and lynx.

But this is logic of Pleistocene rewilding. It is to say that we can somehow turn back the clock on that happened long before North America had cities and agriculture and way long before the continent was divided into nation-states.

Indeed, while we’re theorizing about Pleistocene rewilding, we’re not really coming to terms with that fact that Pre-Columbian rewilding is a project that will only go so far. Yes, we’ll have wolves come back to the Upper Midwest and the Western States.

But no one is seriously considering restoring grizzly bears to Texas or even attempt to bring back wolverines to Michigan.

We cannot handle that idea of wildlife now. That we have managed to hold onto so many wild places and restore so many wildlife species is a certain greatness about the United States. However, this feature is one that always exists in tension, one that must be recognized and fully understood.

Isle Royal in 2019 is not the same as Isle Royal in 1960, which was not the same as Isle Royale when the loggers and the miners came.

And if that one island is so different, imagine how different the entire continent of North America has become since the Pleistocene gave way to the Holocene, which has now giving away to the Anthropocene.

There is a sadness in knowing that things pass, and we certainly have a moral duty to prevent extinction and to preserve what ecosystems we can.

But we should understand that what we’re preserving was never timeless, and even in our attempts at restoration, we aren’t always going back to the known original condition of a place. We often go back to what seemed wondrous and pure and wild.

And if we can understand this simple fact, maybe we can get a handle on what our species continues to do to the planet and the rest of life that resides here with us. We have done much, but we shouldn’t assume that we are preserving any kind of stasis.

I write these words from the northern edge of Appalachian Ohio, awaiting the arrival of the nine-banded armadillo, which will some day come working its way up from North Carolina and Tennessee into Virginia and then West Virginia.  Xenarthan,  the “strange jointed stranger”  with roots in Latin America, it will come scurrying along into this part of the world.

What it may change in our ecosystems, I cannot guess. But it is coming.  When it arrives, it will roam where wolves once howled and elk bulls bugled.

And its story on the land will be one to note. It will not be timeless. It will a temporal as the fleetingness of existence, a bit of the faunal guild of the Anthropocene making a name for itself in a new land, just as those Siberian hunters did all those thousands of years ago.

 

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