Wildlife

Wildlife Wednesday: can the mighty muskox survive its greatest test yet?

Plus: a sea lion and an octopus fight to the death, new luminescence discovered in sea cucumbers, volcanic winters may have caused dinosaur extinction, and the white bison gene is revealed.

  • Dec 06, 2023
  • 986 words
  • 4 minutes
DNA from ancient muskox shows today's muskox are lacking in genetic diversity. (Photo: Public Domain)
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Muskox, the tundra’s ultimate survivors, have survived ice ages ending and extreme commercial hunting when many species did not. They’ve been reduced to numbers as low as 400, tucked away in pockets of Canada and northeastern Greenland, yet rebounded. But these challenges have taken their toll. 

Evolutionary biologists at the University of Copenhagen have delved into the muskox’s history by collecting DNA samples from remote parts of Canada and Greenland — and one 21,000-year-old sample from Wrangel Island, Siberia. Using these samples, the researchers analyzed the whole genome of more than 100 muskoxen. They found that the muskox has lost a big proportion of its genetic diversity over the past 20,000 years. Even the most diverse of present-day muskoxen have only about a third of the diversity that the Siberian muskox had 21,000 years ago. 

They are the least diverse ungulate, and in a range where most top predators usually end. Yet, unlike other species with similar genetic diversity such as the cheetah, snow leopard or white rhino, the muskox is widespread and counts close to 170,000 animals.

They owe this to their adaptation to the harshest of environments Earth has to offer. However, with the Arctic climate heating rapidly, muskox are likely to face their biggest challenge yet. Their major food sources could be cut off, and diseases previously held at bay by the cold of the Arctic are now spreading further north. With their genetic diversity so low, can these shaggy survivors come out on top once more?

A tough meal

While sea lions hunt octopuses, it doesn't always go smoothly. (Photo: GRID Arendal/Flickr [CC BY-NC-SA 2.0 DEED ])
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One Nanaimo, B.C., resident had a swim to remember last month when she came across an octopus and a sea lion locked in battle. In a three-and-half-minute video that now has over 300,000 views, Lindey Bryant captured the scene in the Strait of Georgia, off the coast of Vancouver Island, which showed the large marine mammal thrashing and writhing in the water. Seemingly in distress, the sea lion was in the middle of hunting a particularly tricky prey — a large octopus. 

According to marine biologist Sherry Tamone, the octopus is able to “wrap itself around the head of the sea lion and bite pretty fiercely. Their beak looks a bit like that of a parrot and each bite delivers nasty chemicals.”

The challenge for a sea lion is to swallow an octopus without the octopus getting its eight arms around the sea lion’s head, something the sea lion will attempt to overcome by taking off one octopus arm at a time. 

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Shine bright like a cucumber

A spectacular image of a benthopelagic sea cucumber swimming in the near freezing waters of the abyss. (Photo: courtesy of NOAA Okeanos Explorer Program, INDEX-SATAL 2010 [Public Domain])
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A new book by a group of experts in their respective fields, titled The World of the Sea Cucumbers and published by Elsevier Science, has shone a light on deep-sea sea cucumbers — and the sea cucumbers have shone a light right back.

For the first time, 10 deep-sea species of sea cucumber have been shown to have previously unknown luminosity, suggesting an underestimated level of diversity. Deep-sea sea cucumbers have been lighting up oceans since the Jurassic period about 180 million years ago and far outshine their shallow-water relatives, which often appear drab in comparison. The book illustrates the fantastic colours on display with photographs taken using a deep-sea probe equipped with a specialized camera.

According to Nagoya University professor and contributor Manabu Bessho-Uehara, the researchers involved in the book hope readers will gain an understanding that, despite living in the deep sea, sea cucumbers will face likely heightened impact from humans via commercial drilling and exploitation.

Dinosaur demise

Volcanic winters may have triggered the downfall of dinosaurs. (Photo: Free public domain CC0 photo)
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Did they go out with a bang? University of McGill researchers have challenged the current understanding of dinosaur extinction by unearthing a link between ancient volcanic eruptions and a subsequent period of climate change — known as a volcanic winter — that may have beaten the asteroid to the punch.

The research team studied a series of eruptions that occurred in the Deccan Traps — a vast plateau in western India formed by molten lava — some 65 million years ago and 200,000 years prior to dinosaur extinction. Erupting about one million cubic kilometres of rock and releasing sulfur into the atmosphere, they may have played a key role in cooling the global climate at the time. 

“Climatic conditions were almost certainly unstable, with repeated volcanic winters that could have lasted decades, prior to the extinction of the dinosaurs,” says McGill professor in Earth and planetary sciences and study co-author Don Baker. “This instability would have made life difficult for all plants and animals and set the stage for the dinosaur extinction event.”

Mapping the white bison

Texas A&M University scientists have unlocked the gene that causes albinism in North American Bison. (Photo: Hans Watson/Flickr [CC BY-NC-SA 2.0 DEED]
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A team of scientists from the Texas A&M School of Veterinary Medicine & Biomedical Sciences have developed the most comprehensive genome yet for the North American bison, and in doing so discovered the gene responsible for albinism (a lack of pigment in the body that causes white fur and red eyes) in bison. 

Venerated for thousands of years by the Lakota and other Indigenous Peoples of the Great Plains and Canadian Prairies, the birth of a white bison is celebrated as a sacred omen to this day. White bison can be born as a result of rare genetic conditions such as leucism (partial lack of pigment, causing white fur and blue eyes) or albinism, or through crossbreeding with cattle. The researchers’ study, published in G3: Genes, Genomes and Genetics, used the high-resolution reference genome they created for the North American bison to produce a test for genetic mutations, starting with albinism.

As well as identifying the gene that causes albinism in bison, the scientists found out that the mutation causes an important enzyme to cease functioning correctly, causing the lack of skin pigmentation. 

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