News and Notes About Science
Posted August 20, 2018 4:40 p.m. EDT
Trapped in 99-Million-Year-Old Amber, a Beetle With Pilfered Pollen
Bees and butterflies are praised for their pollination prowess. But millions of years before they ever flirted with a flower, beetles were one of the world’s pre-eminent pollinators.
Among the plethora of prehistoric plants they helped fertilize were cycads, which look like a mix between palms and ferns, though they are more closely related to pines. They have thick trunks and pineapple-shaped cones, and they are crowned with featherlike leaves.
Researchers knew from studying modern cycads that they were pollinated by beetles. Now, for the first time, paleontologists have found trapped in amber from Myanmar a 99-million-year-old beetle preserved with pilfered pollen from a cycad. They reported their find recently in the journal Current Biology.
“Finding this ancient relationship, it’s like a dream come true,” said Chenyang Cai, a research fellow at the University of Bristol in England.
Cai started studying the amber while doing research in China. Stuck inside was a 2-millimeter-long insect, known as a boganiid beetle. These beetles have a tiny cavity filled with hair at the base of their mandibles that acts like a pocket for collecting pollen.
When he was done cutting, trimming and polishing the amber, Cai had what was essentially a biological sample mounted on a golden glass slide. He placed the fossil under a microscope and examined it at 400 times magnification. There, he found the beetle’s mandible pocket. And surprisingly, he saw dozens of specks of pollen, some even clustered in clumps, alongside the beetle.
“I was very excited. I just wanted to know what was this pollen,” Cai said. “It’s not on the body of the beetle, but it’s very close to the beetle and to its mouth part,” he said.
He noted that the pollen may have once been on the beetle, but it could have slid off as the pair were engulfed by tree resin.
Cai contacted Liqin Li, who studies ancient pollen at the Chinese Academy of Sciences and is an author on the paper. By observing the long grooves on the oval-shaped grains, Li identified the pollen as belonging to an ancient cycad.
— NICHOLAS ST. FLEUR
Making a Laboratory of Reindeer Carcasses
On a chilly day in August 2016, more than 300 reindeer dropped dead on a mountain plateau in Norway. They died by lightning, which coursed through the wet ground, climbed up their legs and fatally jolted their hearts.
Their bodies soon became a soup of nutrients and a rich feeding ground for scavengers, which dropped feces packed with seeds all around the carcasses.
That patch of land now has the potential to spawn new plant diversity from across a broad landscape, Norwegian scientists reported recently in Biology Letters.
“From death comes life,” said Sam Steyaert, a researcher at the University of South-Eastern Norway and the Norwegian University of Life Sciences, and an author of the paper.
He and a group of collaborators started a self-funded project. They named it REINCAR, which was short for reindeer carcasses, but also the start of the word reincarnation.
That October, the scientists set up their field laboratory. Each visit, they arrived to hundreds of ravens and crows, many smaller birds and the occasional circling eagle or buzzard. Their camera traps captured foxes and wolverines, among other visitors.
The cadavers still bore plenty of flesh but were ballooned from the gases released during decomposition and contained “all kinds of juice — and thousands and thousands of maggots, of course,” Steyaert said.
There were also piles of feces everywhere.
From survey plots, the scientists found that fox and bird feces were most concentrated in carrion-dense areas, supporting their suspicion that carcasses were magnets for scavengers. They confirmed in the lab that a large portion of crowberry seeds found in the feces could grow into seedlings.
The crowberry plant is a keystone species in the alpine tundra, serving as an important food source to many creatures and influencing nutrient cycles.
It is thought that their seedlings, and those of similar plants, require bare, nutrient-dense soil to germinate.
Incidentally, “that’s exactly what the carcasses are creating,” Steyaert said, explaining that abrupt shifts in soil nutrients and acidity from rotting carrion kills vegetation.
Add a bunch of roaming scavengers that bring in a mix of seeds from a wide area, and you basically have “directed seed dispersal to the ideal germination spot,” he said.
His team suspects the site will become a hot spot of genetic diversity for plants, as well as nutrients and microbes that scavengers help redistribute.
— STEPH YIN
Friendly Foxes’ Genes Offer Hints to How Dogs Became Domesticated
Tame foxes offer a tantalizing window into the nature of domestication. Starting around 1960, Russian scientists took farm-bred foxes and began to breed them selectively, not for better fur, but for friendliness toward humans.
The result is a strain of foxes that appears to take just as much pleasure in the company of people as your average golden retriever. Their story was chronicled last year in a book whose co-author, Lyudmila Trut, is one of the scientists who conducted the experiment.
The tame foxes may seem like irresistible pets. But they are still nocturnal, not easily housebroken and not really well-suited to live in a house with human beings, said Anna V. Kukekova, of the University of Illinois, who studies the genetics of the foxes.
They are, however, an obvious resource for genetic studies that aim to tease out some of the genes involved in domestication, particularly in dogs. Foxes are canids, like wolves, dogs and the extinct wolves that are thought to have given rise to dogs.
Kukekova and a team of scientists in the United States, Russia and China sequenced the red fox genome for the first time and then compared three strains of red foxes — farm bred, selected for tameness and selected for aggressiveness. All three strains were bred by the Institute of Cytology and Genetics of the Russian Academy of Sciences.
Kukekova and colleagues identified 103 regions of DNA that stood out as having been under selective pressure in the breeding, in which only the friendliest pups were allowed to mate. She also picked one gene that seemed to be a good candidate in selecting for tameness, called SorCS1. They reported their work in Nature Ecology & Evolution.
The gene is involved in regulating how the connections between brain cells work, which makes sense for a gene involved in social behavior. Other genes of interest are connected to human illnesses that affect behavior, like autism.
But determining how such genes might fit into domestication is a very complicated enterprise, Kukekova said. “The domestic dog is selected for so many different things,” she said. The fox is only selected for friendliness.
— JAMES GORMAN
For Online Daters, Women Peak at 18 While Men Peak at 50, Study Finds
In a new study about online dating published in the journal Science Advances, researchers studied the “desirability” of male and female users, based on how many messages nearly 200,000 users, all of whom were seeking opposite-sex partners, got over one month on a “popular, free online-dating service” — and if those sending the messages were desirable based on the same criteria.
The researchers determined that while men’s sexual desirability peaks at age 50, women’s starts high at 18 and falls from there.
“The age gradient for women definitely surprised us — both in terms of the fact that it steadily declined from the time women were 18 to the time they were 65, and also how steep it was,” said Elizabeth Bruch, an associate professor of sociology at the University of Michigan and an author of the study.
This study is not an anomaly. The study results echoed data shared by the dating behemoth OkCupid in 2010, in which the service found that men from the ages of 22-30 focus almost entirely on women who are younger than them.
“The median 30-year-old man spends as much time messaging teenage girls as he does women his own age,” OkCupid wrote in a blog post at the time.
OkCupid also reported that as a man gets older, he searches for relatively younger and younger women, while his upper acceptable age limit hovers just above his own age.
“The male fixation on youth distorts the dating pool,” OkCupid concluded.
Michelle Drouin, a developmental psychologist who focuses on technology and relationships, was not surprised by the new study — in part because they “align with evolutionary theories of mating” in which youth suggests fertility, she said.
Drouin pointed out, though, that there are also theories that suggest that “men are just less interested in earning potential or power, and more interested in physical attractiveness.”
— MAYA SALAM
Paternity Tests at the Penguin House
Roto and Copper, two gentoo penguins at Loveland Living Planet Aquarium in Utah, cared for three children together, taking turns feeding them. They are a social pair, just like Coco and Gossamer, a neighboring penguin couple that raised their own chicks.
Or did they?
We tend to think of penguins as monogamous, with social bonds formed between two parents for life. But researchers have discovered that penguins in captivity, like some species in the wild, sometimes stray. After sampling the DNA of 19 gentoo penguins at the aquarium, researchers revealed recently in the journal ZooBiology that Roto is the father of two chicks believed to be Gossamer’s offspring.
“We’ll go back to the classic movies where the male gives the female a rock and they start to build their nest with it, and they are totally monogamous,” Steve Vogel, the aquarium’s zoological operations director said, “and that is not true 20 percent of the time.” At least not at this aquarium.
These penguins are set to be part of a program pairing the most genetically diverse animals from different facilities, like people in a matchmaking service, to ensure a strong, healthy penguin population in case this species ever goes extinct. Although gentoo penguins are doing relatively OK in the wild, other species face threats from climate change, overfishing, oil drilling and other factors.
For this penguin dating service to work, documenting familial lineages is critical to avoiding inbreeding. And while the sample size is small, the study suggests that using DNA evidence to confirm behavioral observations may be the best way to ensure healthy penguin populations of the future.
At the aquarium, staff monitor the penguins like producers on a reality TV show. When they spot two penguins engaging in mating behavior, they call in a “code Romeo.” The signal summons an animal keeper, who determines as best she can which two penguins are getting busy, and documents it in the Gentoo Penguin Studbook, a database shared among zoos and aquariums that will be used to make the most genetically diverse matches.
At Loveland, staff started noticing some penguins mating outside their social pairs.
This called for paternity testing.
Of eight offspring they tested, two had a biological father that was not their social father. In other words, Roto and Coco had been sneaking around. Another rogue female had been mating with two different males too — even though the males were in stable social pairs.
— JOANNA KLEIN