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Kate Horowitz

Scientists Discover That Lichens Are Symbiotic Threesomes

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Kate Horowitz

When’s the last time you really looked at lichen? If you’re like most people, the answer is probably “never.” That’s a shame, because these unassuming little organisms are useful, amazing, and, scientists now say, a lot more complicated than we previously realized. They published their findings in the journal Science

You might not know it from the way we treat these organisms today, but humans and lichens have a long and close relationship. Cultures around the world have used lichens for thousands of years as medicine, dye, and food. Some myths say the first lichens were really scabs scraped onto a rock from the buttocks of a hero, while others say they're lizard sperm. (Do we have your attention yet?)   

So—putting aside the lizard sperm theory—what is lichen, exactly? That depends on who, and when, you ask. Naturalists in the first half of the 19th century were quite confident that they were dealing with a plant, and were scandalized by Swiss botanist Simon Schwendener’s 1868 announcement that lichens were cooperative organisms composed of one type of fungus and one type of microscopic alga. Eventually, Schwendener won over his critics. His findings entered the scientific canon, and there they stayed … until last week, when researchers in Montana and elsewhere said they’d identified a third member of the lichen household.

Microbiologist Toby Spribille of the University of Montana was part of the team shaking up the lichen establishment. “There’s been over 140 years of microscopy,” Spribille told Ed Yong at The Atlantic. “The idea that there’s something so fundamental that people have been missing is stunning.”  

Spribille and his colleagues might have missed it too, had they not taken an interest in a local pair of lichens called Bryoria tortuosa and Bryoria fremontii. The two are closely related but easy enough to tell apart—B. tortuosa is yellow, while B. fremontii is brown—and that’s really good, because B. tortuosa is toxic, while B. fremontii was historically used as food. 

B. tortuosa. Image credit: Tim Wheeler

A few years ago, researchers decided to take a look at the two species’ genes to see where they diverged. Conclusion? They didn’t. According to their genetic barcode analysis, toxic B. tortuosa and edible B. fremontii were just two different names for the same species. 

That didn’t sit right with Spribille and his colleagues, who had begun using advanced genomic techniques to understand cooperative relationships between insects and other organisms. They decided to take another crack at the puzzle using the latest sequencing technology. 

The team went out into the wilds of Montana and collected samples of both lichen types, then ground them up and sequenced their RNA. What they found contradicted not only the single-species theory, but also the one-fungus/one-photosynthesizing-microbe definition of lichen-hood. Each lichen’s genetic code contained not one, but two different types of fungus—and that second fungus was far more prevalent in deadly B. tortuosa.

To make sure they understood what they were seeing, the team then analyzed the DNA of lichen species from all over the world. Most of those species—from 52 lichen genera on six continents—also included that sneaky second fungus, a basidiomycete yeast. Of the 52 genera, all but 10 are in a single lichen family: Parmeliaceae.  

“We found it in everything,” Spribille told Gizmodo. “From Alaska to Ethiopia to Antarctica, it always was there.” 

He notes that overlooking the presence of the silent fungus partner may be the reason scientists have historically had so much trouble growing lichens in the lab. 

Whether toxic or edible, he says, every lichen is remarkable. “One thing that sets lichen apart from all other symbioses is that all the components are microbes. But when they come together, they form something self-replicating and beautiful that you can hold in your hand.”

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Animals
Why Do Female Spotted Hyenas Give Birth Through Their Pseudo-Penises?
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YouTube

At the zoo, you can sometimes tell the difference between male and female animals by noting their physical size, their behavior, and yes, their nether regions. Hyenas, however, flip the script: Not only are lady spotted hyenas bigger and meaner than their male counterparts, ruling the pack with an iron paw, they also sport what appear to be penises—shaft, scrotum, and all.

"Appear" is the key word here: These 7-inch-long phalluses don't produce sperm, so they're technically really long clitorises in disguise. But why do female hyenas have them? And do they actually have to (gulp) give birth through them? Wouldn't that hurt … a lot?

The short answers to these questions are, respectively, "We don't know," "Yes," and "OW." Longer answers can be found in this MinuteEarth video, which provides the full lowdown on hyena sex. Don't say we didn't warn you.

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science
Are Sex, Drugs, and Rock 'n' Roll Really Linked? Researchers Investigate
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Around the world, sex, drugs, and rock 'n' roll are said to go hand-in-hand. But do they? As PsyPost reports, a pair of Pennsylvania psychologists recently dove into the empirical evidence tying the three together, asking college students to talk about their drug use, sex lives, and music preferences and talents to suss out whether people who play and enjoy rock music really do have more active sex lives and drug use.

Published in the journal Human Ethnology Bulletin, the study [PDF] of 467 students relied on self-reporting, which isn't typically the most reliable evidence—people are wont to exaggerate how often they've had sex, for instance—but the survey also asked them about their desires, posing questions like "If you could, how frequently would you have sex?" It also asked about how often the students drank and what drugs they had tried in their lifetimes. They also described their musical experience and what kind of music they listened to.

The results were mixed, but the researchers identified a relationship between liking faster, "harder" music and having more sex and doing more drugs. Acoustic indie rock aficionados weren't getting quite as wild as heavy metal fans. High-tempo-music lovers were more likely to have taken hallucinogenic drugs like LSD, for example, and tended to have had more sexual partners in the previous year than people who favored slower types of music. According to the study, previous research has found that attention-seeking people are more likely to enjoy "hard" music.

The study didn't have a diverse enough group either in age or in ethnicity to really begin to make sweeping generalizations about humans, especially since college students (the participants were between 18 and 25) tend to engage in more risky behaviors in general. But this could lay the groundwork for future research into the topic. Until then, it might be more accurate to change the phrase to "sex, drugs, and heavy metal."

[h/t PsyPost]

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