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Endangered Sawfish Reproduce Through "Virgin Birth"

You know the drill: When a male and a female love each other very much—or are compelled by nature—they make a baby together. But sometimes a female becomes pregnant without any input from a male. So-called “virgin births” may seem miraculous, but they’re actually the product of parthenogenesis, a form of asexual reproduction in which an embryo grows and develops without fertilization.  

Parthenogenesis has been observed in some invertebrates like honeybees and scorpions, and very rarely among captive vertebrates like snakes, lizards, and birds. Now researchers at Stony Brook University say they’ve discovered the first known example of parthenogenesis in wild vertebrates—and the phenomenon could be more common than we think.

Named for what looks like a massive chainsaw blade protruding out of its face, the smalltooth sawfish, which lives in southern Florida, was first listed as an endangered species in 2003. Its numbers have been drastically reduced thanks to overfishing and habitat loss. Andrew Fields, a Ph.D. candidate at Stony Brook's School of Marine and Atmospheric Science, wanted to get a sense of exactly how many sawfish still exist.

“We wanted to be ready to say, ‘This is happening, and we need to do something now before they go extinct,’” Fields told mental_floss.

They may have set out to do a population count, but they found much more. As they document in Current Biology, Fields and his team examined sawfish DNA for signs of inbreeding, which can indicate a dwindling number of individuals in a species. In the process they discovered that about 3 percent of the sawfish they studied were solely the offspring of their mothers and had no genetic contribution from a male.

In normal sexual reproduction, the female egg ejects half its chromosomes through a series of cell divisions after it matures, making up the difference by combining with the chromosomes from the male sperm. In parthenogenesis, another female cell known as the polar body provides the second half of chromosomes. Although the offspring will have two sets of chromosomes, they will be identical.

Perhaps even more surprising is that the fatherless sawfish seem relatively normal. “We don’t have any physical proof they’re any different, which is strange because the general theory right now is [that] parthenogenetic offspring are not fit, and so they don’t survive in the wild,” Fields says. “So this is kind of a big step.”

But why do “virgin births” happen? Until now, sexless reproduction in vertebrates had only been observed in captivity, so the standing theory has been that the special stresses of captivity are the cause, Fields says. In 2001, for example, a hammerhead shark at a Nebraska zoo gave birth despite not having contact with a male for three years.

But these new findings suggest that maybe it’s not the stress of being in captivity that prompts parthenogenesis, but a lack of males. Perhaps a virgin birth is a dwindling species’ last-ditch effort to avoid extinction.

Unfortunately for the sawfish, parthenogenesis probably won’t help keep the population alive. While the parthenogenetic fish seem normal, they are all female, which could exacerbate the problem of male scarcity. “If the sex ratio flips enough, it could help with the extinction,” Fields says.

Fields and his team are urging other researchers to join the hunt for examples of virgin births in wild vertebrates by reexamining existing DNA evidence. “A lot of shark populations have been fished for the shark fin trade, so it’s possible we could start looking at a number of shark species,” Fields says. “It may be the data is out there, but nobody has looked for it because we think it doesn’t happen.” 

[h/t The Guardian]

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Animals
Why Tiny 'Hedgehog Highways' Are Popping Up Around London
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Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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