Self-Perpetuating Female Salamanders Are Better Off Without Males, Study Finds

Human sex is fascinating, but compared to other animals, the way we reproduce is boring. Take the mole salamander, for example. Some all-female populations of salamanders have figured out a way to make copies of themselves without bothering to involve males. Now, ordinarily, that kind of reproduction shrinks the gene pool and makes animals less able to adapt. But researchers, who published their findings in the Journal of Zoology, say the opposite is true for some mole salamanders, which have complex genes and can regenerate body parts faster than their relatives.

How could an all-female group add to its gene pool? Two words: secondhand sperm. Male salamanders in the genus Ambystona are sloppy creatures, and will leave pools of their genetic material lying around on leaves and twigs. If a female salamander happens to find that sperm, she might just put it to use. And it gets even weirder: that male doesn’t even have to belong to her species. A cloned female could carry DNA from several different species at once—and it’s this capacity that may make her special.

To learn more, researchers collected six blobs of salamander eggs from wetland environments in Ohio. Three of the egg masses were taken from populations of sexually reproducing male and female small-mouth salamanders (A. texanum). The other three egg blobs were collected from all-female (or unisexual) groups in the same area. All the eggs were brought back to the lab and their inhabitants reared to adulthood.

Denton palling around with one of his gifted subjects. Image Credit: Kevin Fitzsimmons, The Ohio State University

Once the salamanders were 10 to 12 months old, the researchers took them out and cut a small piece from each one’s tail. The tail snips from unisexual salamanders were used to test their DNA and identify their ancestry. Now humans, most other mammals, and many salamanders are diploid: that is, each individual has two sets of chromosomes, one from each parent. Salamanders from the no-boys-allowed club, on the other hand, had three sets apiece, taken from two different species (A. laterale and A. jeffersonium).

The researchers monitored the salamanders for weeks, measuring their tails to see if and how quickly they were growing back. A gap soon emerged. After seven weeks, the self-cloning salamanders’ tails were almost completely regenerated. But the small-mouths’ tails wouldn’t finish growing back for another four weeks after that. To put it another way: members of the all-female salamander group regenerated their tails 1.5 times faster than the small-mouths could.

"I don't think we expected it to happen so fast," Ohio State biologist and study co-author Robert Denton said in a press statement.

A salamander’s tail is not just for show; it’s a functional appendage. As juveniles in the water, salamander larvae need tails to propel them through the water in order to evade predators. As adults, they can use their tails to distract opponents long enough to get away. So the ability to grow back a tail quickly is kind of a huge advantage.

"They get injured a lot," said biology student and study leader Monica Saccucci. "If you can't regenerate, you're dead.”

Saccucci, Denton, and their colleagues are quite impressed with the unisexual salamanders, but remain unsure of how they’re doing it. Is having sex with yourself the key to getting ahead? Is it the fact that each salamander lady is a hybrid? Are their ancestral species just really cool? Is it all those chromosomes they’re hoarding?

"Ideally, we'd love to compare unisexuals with different numbers of genomes from different species against those sexual species," Denton told mental_floss in an email. But he does suspect that the single-sex lifestyle has something to do with it.

"We do have other physiological data (locomotor endurance on treadmills) that suggests that unisexuals are different as a group when compared to multiple sexual species, which might suggest that the regeneration difference here is due more to polyploidy than genome composition," Denton said. "Overall, there is a great deal of work to be done disentangling the strange genomic makeup of these animals."

Roadside Bear Statue in Wales is So Lifelike That Safety Officials Want It Removed

Wooden bear statue.

There are no real bears in the British Isles for residents to worry about, but a statue of one in the small Welsh town of Llanwrtyd Wells has become a cause of concern. As The Telegraph reports, the statue is so convincing that it's scaring drivers, causing at least one motorist to crash her car. Now road safety officials are demanding it be removed.

The 10-foot wooden statue has been a fixture on the roadside for at least 15 years. It made headlines in May of 2018 when a woman driving her car saw the landmark and took it to be the real thing. She was so startled that she veered off the road and into a street sign.

After the incident, she complained about the bear to highways officials who agreed that it poses a safety threat and should be removed. But the small town isn't giving in to the Welsh government's demands so quickly.

The bear statue was originally erected on the site of a now-defunct wool mill. Even though the mill has since closed, locals still see the statue as an important landmark. Llanwrtyd Wells councilor Peter James called it an "iconic gateway of the town," according to The Telegraph.

Another town resident, who wished to remain anonymous, told The Telegraph that the woman who crashed her car had been a tourist from Canada where bears are common. Bear were hunted to extinction in Britain about 1000 years ago, so local drivers have no reason to look out for the real animals on the side of the road.

The statue remains in its old spot, but Welsh government officials plan to remove it themselves if the town doesn't cooperate. For now, temporary traffic lights have been set up around the site of the accident to prevent any similar incidents.

[h/t The Telegraph]

10 Scientific Benefits of Being a Dog Owner

The bickering between cat people and dog people is ongoing and vicious, but in the end, we're all better off for loving a pet. But if anyone tries to poo-poo your pooch, know that there are some scientific reasons that they're man's best friend.


Dog snuggling on a bed with its person.

If cleaning commercials are to be believed, humanity is in the midst of a war against germs—and we shouldn't stop until every single one is dead. In reality, the amount of disinfecting we do is making us sicker; since our bodies are exposed to a less diverse mix of germs, our entire microbiome is messed up. Fortunately, dogs are covered in germs! Having a dog in the house means more diverse bacteria enters the home and gets inside the occupants (one study found "dog-related biodiversity" is especially high on pillowcases). In turn, people with dogs seem to get ill less frequently and less severely than people—especially children—with cats or no pets.


Child and mother playing with a dog on a bed.

While dog dander can be a trigger for people with allergies, growing up in a house with a dog makes children less likely to develop allergies over the course of their lives. And the benefits can start during gestation; a 2017 study published in the journal Microbiome found that a bacterial exchange happened between women who lived with pets (largely dogs) during pregnancy and their children, regardless of type of birth or whether the child was breastfed, and even if the pet was not in the home after the birth of the child. Those children tested had two bacteria, Ruminococcus and Oscillospira, that reduce the risk of common allergies, asthma, and obesity, and they were less likely to develop eczema.


Woman doing yoga with her dog.

Everything about owning a dog seems to lend itself to better heart health. Just the act of petting a dog lowers heart rate and blood pressure. A 2017 Chinese study found a link between dog ownership and reduced risk of coronary artery disease, while other studies show pet owners have slightly lower cholesterol and are more likely to survive a heart attack.


Person running in field with a dog.

While other pets have positive effects on your health as well, dogs have the added benefit of needing to be walked and played with numerous times a day. This means that many dog owners are getting 30 minutes of exercise a day, lowering their risk of cardiovascular disease.


Woman cuddling her dog.

Dog owners are less likely to suffer from depression than non-pet owners. Even for those people who are clinically depressed, having a pet to take care of can help them out of a depressive episode. Since taking care of a dog requires a routine and forces you to stay at least a little active, dog owners are more likely to interact with others and have an increased sense of well-being while tending to their pet. The interaction with and love received from a dog can also help people stay positive. Even the mere act of looking at your pet increases the amount of oxytocin, the "feel good" chemical, in the brain.


Large bulldog licking a laughing man.

Not only does dog ownership indirectly tell others that you're trustworthy, your trusty companion can help facilitate friendships and social networks. A 2015 study published in PLOS One found that dogs can be both the catalyst for sparking new relationships and also the means for keeping social networks thriving. One study even showed that those with dogs also had closer and more supportive relationships with the people in their lives.


Man high-fiving his dog.

Your dog could save your life one day: It seems that our canine friends have the ability to smell cancer in the human body. Stories abound of owners whose dogs kept sniffing or licking a mole or lump on their body so they got it checked out, discovering it was cancerous. The anecdotal evidence has been backed up by scientific studies, and some dogs are now trained to detect cancer.


Woman working on a computer while petting a dog.

The benefits of bringing a dog to work are so increasingly obvious that more companies are catching on. Studies show that people who interact with a pet while working have lower stress levels throughout the day, while people who do not bring a pet see their stress levels increase over time. Dogs in the office also lead to people taking more breaks, to play with or walk the dog, which makes them more energized when they return to work. This, in turn, has been shown to lead to much greater productivity and job satisfaction.


Man running in surf with dog.

The kind of dog you have says a lot about your personality. A study in England found a very clear correlation between people's personalities and what type of dogs they owned; for example, people who owned toy dogs tended to be more intelligent, while owners of utility dogs like Dalmatians and bulldogs were the most conscientious. Other studies have found that dog owners in general are more outgoing and friendly than cat owners.


A young boy having fun with his dog.

Though one 2003 study found that there was no link between pet ownership and empathy in a group of children, a 2017 study of 1000 7- to 12-year-olds found that pet attachment of any kind encouraged compassion and positive attitudes toward animals, which promoted better well-being for both the child and the pet. Children with dogs scored the highest for pet attachment, and the study notes that "dogs may help children to regulate their emotions because they can trigger and respond to a child's attachment related behavior." And, of course, only one pet will happily play fetch with a toddler.

A version of this story originally ran in 2015.


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