Reanalysis of global amphibian crisis study finds important flaws

by University of California - Berkeley

Rana clamitans. Credit: Max Lambert.

Though biodiversity is in crisis globally, amphibians in particular face a variety of threats. One such threat comes from pathogens like the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Bd causes chytridiomycosis, a disease that research indicates contributes to the decline of some amphibians. New research, however, now calls into question some prior evidence that links the widespread pathogen to hundreds of amphibian declines.


Last year in the journal Science, a research review by Scheele et al. concluded that Bd caused the decline of at least 501 amphibian species, of which 90 have gone extinct. That paper suggested that species losses due to Bd are "orders of magnitude greater than for other high-profile wildlife pathogens." But a recent reanalysis led by Berkeley researchers found that Scheele et al."s main conclusions lack evidence and are unreproducible.

In a Comment published today in Science, the group conducting the reanalysis—including lead authors Max Lambert and Molly Womack, who are postdocs in the lab of professor Erica Rosenblum in the Department of Environmental Science, Policy, and Management (ESPM)—identified a number of data deficiencies and methodological issues in the Scheele et al. study. Working through the methods and datasets, they faced challenges in reproducing conclusions while identifying numerous instances of missing data. In some cases, data gaps failed to link Bd to species declines—even for many species which were previously reported with high certainty that Bd was the cause.

Atelopus zeteki. Credit: Allison Byrne.

Lambert and Womack note that their reanalysis does not minimize the role Bd has played in amphibian declines and that "chytridiomycosis has irrefutably harmed amphibians."

A number of co-authors involved in the reanalysis had previously studied the harmful effects of the chytrid fungus on amphibians in California and Central America. For some species, the data make clear that amphibian chytrid fungus, which has received tremendous attention, has contributed to declines. However, Lambert, Womack, and their collaborators found that the evidence in Scheele et al."s analysis is negligible—or even absent—for many important species.

They state that it remains unclear exactly how many and which amphibian species have been harmed by Bd. Relative to other threats that amphibians face, the role chytrid plays in global declines is also uncertain. In many cases, according to the Science comment, the cause of amphibian declines remains a mystery.

The reanalysis authors argue that transparent data collection and analysis are crucial—both for science and conservation efforts. "It is more critical than ever for scientists to provide responsible narratives based on transparent and reproducible data and methods," says Lambert. "Doing so will produce better science and more effective conservation."Mass amphibian extinctions globally caused by fungal disease

More information: Max R. Lambert et al. Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity", Science (2020). DOI: 10.1126/science.aay1838

INTERSPECIES SEX 

Female toads seek a good man—even if he's another species

by Brian Owens, Inside Science, American Institute of Physics

Credit: CC0 Public Domain

The one thing about species that most people probably remember from high school science class is that when it comes to sex, they generally stick to their own kind. Hybrids happen, but they are usually thought to be accidental, and the results typically have drawbacks—think of how a horse crossed with a donkey results in a sterile mule.

But the reality is more complicated than that. Karin Pfennig, an evolutionary biologist at the University of North Carolina at Chapel Hill, has for years been observing something strange in the southwestern U.S. Female plains spadefoot toads sometimes choose to ignore the males of their own species, and instead mate with males from a closely related species, the Mexican spadefoot toad.

The toads do this under very specific circumstances, said Catherine Chen, a behavioral ecologist who works in Pfennig's lab. Their tadpoles grow up in temporary ponds, and when the ponds are particularly shallow the female plains spadefoots prefer to mate with Mexican spadefoots. This seems to give their offspring a better chance of survival.

"Hybrid tadpoles develop more quickly, so they are more likely reach maturity before the shallow ponds dry up," said Chen.

Now, Chen and Pfennig have found that the female plains spadefoots don't just choose their cross-species dates at random; they look for specific traits that signal they are getting a high-quality mate. They say it is the first time that such cross-species sexual selection has been observed in animals. The work is published today in the journal Science.

In previous mating experiments, the researchers had discovered that hybrid offspring whose fathers' mating call had a slower "pulse rate"—the trilling quality of the call—tended to do better than those whose father had a fast pulse rate. "We wondered, do the females care? Can they tell the difference between high- and low-quality males?" said Chen.

So they placed female plains spadefoots in a simulated pond in the lab, and played recordings of Mexican spadefoot males with different pulse rates. They found that the females did indeed prefer to seek out the males with slower pulse rates.

Chen says they are not sure why males with slower pulse rates make better mates for plains spadefoot females. "Maybe a slower pulse rate means they're in better condition or is associated with certain genes linked to fitness, but we can't say for sure right now," she said.

Interestingly, Mexican spadefoot females have a different idea of what makes a good mate. They don't pay any attention to the pulse rate of the males' call, and instead focus on overall call rate, preferring mates that make more calls in a shorter amount of time—maybe because that takes more energy and so indicates good health.

The hybrid toads that result from crosses between plains females and Mexican males look different from purebred toads, but they are not in the process of forming a new species, said Chen. Hybrid males are sterile, and the hybrid females can mate with either parent species. The researchers don't yet know if these hybrid females have a preference for one or the other, or whether that preference might change under different circumstances.

Marlene Zuk, an evolutionary biologist at the University of Minnesota in St. Paul, says the boundaries between species have always been fuzzier than what most people assume, and the toads' situation is probably not that unique.

"The idea that there is hybridization going on and that it does not result in everyone being struck by lightning is not completely novel," she said. What is new, however, is the idea of females of one species exerting sexual selection on the males of another species—especially by selecting for traits that are different from those preferred by that species' own females. "You've got this whole separate process going on that is independent of what females of that species are doing," she said.

This shows that the effects of hybridization can be much bigger and more important in the development of a species than many biologists thought, said Chen. "We usually think of hybridization as random, and usually bad," she said. "But it doesn't have to be. It can have important evolutionary and ecological effects."Male orb-weaving spiders cannibalized by females may be choosy about mating

---

More information: Catherine Chen et al. Female toads engaging in adaptive hybridization prefer high-quality heterospecifics as mates, Science (2020). DOI: 10.1126/science.aaz5109

Darkness, not cold, likely responsible for dinosaur-killing extinction

by Lauren Lipuma, American Geophysical Union

Roughly 66 million years ago an asteroid slammed into the Yucatan peninsula. New research shows darkness, not cold, likely drove a mass extinction after the impact. Credit: NASA

New research finds soot from global fires ignited by an asteroid impact could have blocked sunlight long enough to drive the mass extinction that killed most life on Earth, including the dinosaurs, 66 million years ago.

The Cretaceous–Paleogene extinction event wiped out about 75 percent of all species on Earth. An asteroid impact at the tip of Mexico's Yucatán Peninsula caused a period of prolonged cold and darkness, called an impact winter, that likely fueled a large part of the mass extinction. But scientists have had a hard time teasing out the details of the impact winter and what the exact mechanism was that killed life on Earth.

A new study in AGU's journal Geophysical Research Letters simulates the contributions of the impact's sulfur, dust, and soot emissions to the extreme darkness and cold of the impact winter. The results show the cold would have been severe but likely not devastating enough to drive a mass extinction. However, soot emissions from global forest fires darkened the sky enough to kill off photosynthesizers at the base of the food web for well over a year, according to the study.

"This low light seems to be a really big signal that would potentially be devastating to life," said Clay Tabor, a geoscientist at the University of Connecticut and lead author of the new study. "It seems like these low light conditions are a probable explanation for a large part of the extinction."

The results help scientists better understand this intriguing mass extinction that ultimately paved the way for humans and other mammals to evolve. But the study also provides insight into what might happen in a nuclear winter scenario, according to Tabor.

"The main driver of a nuclear winter is actually from soot in a similar type situation," Tabor said. "What it really highlights is just how potentially impactful soot can be on the climate system."

The impact and extinction

The Chicxulub asteroid impact spewed clouds of ejecta into the upper atmosphere that then rained back down to Earth. The returning particles would have had enough energy to broil Earth's surface and ignite global forest fires. Soot from the fires, along with sulfur compounds and dust, blocked out sunlight, causing an impact winter lasting several years. Previous research estimates average global temperatures plummeted by at least 26 degrees Celsius (47 degrees Fahrenheit).


Scientists know the extreme darkness and cold were devastating to life on Earth but are still teasing apart which component was more harmful to life and whether the soot, sulfate, or dust particles were most disruptive to the climate.

 

Credit: American Geophysical Union

In the new study, Tabor and his colleagues used a sophisticated climate model to simulate the climatic effects of soot, sulfates, and dust from the impact.

Their results suggest soot emissions from global fires absorbed the most sunlight for the longest amount of time. The model showed soot particles were so good at absorbing sunlight that photosynthesis levels dropped to below one percent of normal for well over a year.

"Based on the properties of soot and its ability to effectively absorb incoming sunlight, it did a very good job at blocking sunlight from reaching the surface," Tabor said. "In comparison to the dust, which didn't stay in the atmosphere for nearly as long, and the sulfur, which didn't block as much light, the soot could actually block almost all light from reaching the surface for at least a year."

A refuge for life

The darkness would have been devastating to photosynthesizers and could explain the mass extinction through a collapse of the food web, according to the researchers. All life on Earth depends on photosynthesizers like plants and algae that harvest energy from sunlight.

Interestingly, the temperature drop likely wasn't as disturbing to life as the darkness, according to the study.

"It's interesting that in their model, soot doesn't necessarily cause a much larger cooling when compared other types of aerosol particles produced by the impact-but soot does cause surface sunlight to decline a lot more," said Manoj Joshi, a climate dynamics professor at the University of East Anglia in the United Kingdom who was not connected to the new study.

In regions like the high latitudes, the results suggest oceans didn't cool significantly more than they do during a normal cycle of the seasons.

"Even though the ocean cools by a decent amount, it doesn't cool by that much everywhere, particularly in the higher latitude regions," Tabor said. "In comparison to the almost two years without photosynthetic activity from soot, it seems to be a secondary importance."

As a result, high latitude coastal regions may have been refuges for life in the months after the impact. Plants and animals living in the Arctic or Antarctic are already used to large temperature swings, extreme cold, and low light, so they may have had a better chance of surviving the impact winter, according to the researcher

Millions of years of soot deposits reveal wildfire cycles related to climate change
More information: Clay R. Tabor et al. Causes and Climatic Consequences of the Impact Winter at the Cretaceous‐Paleogene Boundary, Geophysical Research Letters (2020). DOI: 10.1029/2019GL085572


Julia Brugger et al. Baby, it's cold outside: Climate model simulations of the effects of the asteroid impact at the end of the Cretaceous, Geophysical Research Letters (2016). DOI: 10.1002/2016GL072241
Journal information: Geophysical Research Letters

How oceans and atmospheres move heat around on Earth and other planetary bodies

by Massachusetts Institute of Technology

This visualization shows the Gulf Stream's sea surface currents and and temperatures. Credit: MIT/JPL project entitled Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2)

Imagine a massive mug of cold, dense cream with hot coffee poured on top. Now place it on a rotating table. Over time, the fluids will slowly mix into each other, and heat from the coffee will eventually reach the bottom of the mug. But as most of us impatient coffee drinkers know, stirring the layers together is a more efficient way to distribute the heat and enjoy a beverage that's not scalding hot or ice cold. The key is the swirls, or vortices, that formed in the turbulent liquid.

"If you just waited to see whether molecular diffusion did it, it would take forever and you'll never get your coffee and milk together," says Raffaele Ferrari, Cecil and Ida Green Professor of Oceanography in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

This analogy helps explain a new theory on the intricacies the climate system on Earth—and other rotating planets with atmospheres and/or oceans—outlined in a recent PNAS paper by Ferrari and Basile Gallet, an EAPS visiting researcher from Service de Physique de l'Etat Condensé, CEA Saclay, France.

It may seem intuitive that Earth's sun-baked equator is hot while the relatively sun-deprived poles are cold, with a gradient of temperatures in between. However, the actual span of that temperature gradient is relatively small compared to what it might otherwise be because of the way the Earth system physically transports heat around the globe to cooler regions, moderating the extremes.

Otherwise, "you would have unbearably hot temperatures at the equator and [the temperate latitudes] would be frozen," says Ferrari. "So, the fact that the planet is habitable, as we know it, has to do with heat transport from the equator to the poles."

Yet, despite the importance of global heat flux for maintaining the contemporary climate of Earth, the mechanisms that drive the process are not completely understood. That's where Ferrari and Gallet's recent work comes in: their research lays out a mathematical description of the physics underpinning the role that marine and atmospheric vortices play in redistributing that heat in the global system.

Ferrari and Gallet's work builds on that of another MIT professor, the late meteorologist Norman Phillips, who, in 1956, proposed a set of equations, the "Phillips model," to describe global heat transport. Phillips' model represents the atmopshere and ocean as two layers of different density on top of each other. While these equations capture the development of turbulence and predict the distribution of temperature on Earth with relative accuracy, they are still very complex and need to be solved with computers. The new theory from Ferrari and Gallet provides analytical solutions to the equations and quantitatively predicts local heat flux, energy powering the eddies, and large-scale flow characteristics. And their theoretical framework is scalable, meaning it works for eddies, which are smaller and denser in the ocean, as well as cyclones in the atmosphere that are larger.


Setting the process in motion

The physics behind vortices in your coffee cup differ from those in nature. Fluid media like the atmosphere and ocean are characterized by variations in temperature and density. On a rotating planet, these variations accelerate strong currents, while friction—on the bottom of the ocean and atmosphere—slows them down. This tug of war results in instabilities of the flow of large-scale currents and produces irregular turbulent flows that we experience as ever-changing weather in the atmosphere.

Vortices—closed circular flows of air or water—are born of this instability. In the atmosphere, they're called cyclones and anticyclones (the weather patterns); in the ocean they're called eddies. In both cases, they are transient, ordered formations, emerging somewhat erratically and dissipating over time. As they spin out of the underlying turbulence, they, too, are hindered by friction, causing their eventual dissipation, which completes the transfer of heat from the equator (the top of the hot coffee) to the poles (the bottom of the cream).

Zooming out to the bigger picture

While the Earth system is much more complex than two layers, analyzing heat transport in Phillips' simplified model helps scientists resolve the fundamental physics at play. Ferrari and Gallet found that the heat transport due to vortices, though directionally chaotic, ends up moving heat to the poles faster than a more smooth-flowing system would. According to Ferrari, "vortices do the dog work of moving heat, not disorganized motion (turbulence)."

It would be impossible to mathematically account for every single eddy feature that forms and disappears, so the researchers developed simplified calculations to determine the overall effects of vortex behavior, based on latitude (temperature gradient) and friction parameters. Additionally, they considered each vortex as a single particle in a gas fluid. When they incorporated their calculations into the existing models, the resulting simulations predicted Earth's actual temperature regimes fairly accurately, and revealed that both the formation and function of vortices in the climate system are much more sensitive to frictional drag than anticipated.

Ferrari emphasizes that all modeling endeavors require simplifications and aren't perfect representations of natural systems—as in this instance, with the atmosphere and oceans represented as simple two-layer systems, and the sphericity of the Earth is not accounted for. Even with these drawbacks, Gallet and Ferrari's theory has gotten the attention of other oceanographers.

"Since 1956, meteorologists and oceanographers have tried, and failed, to understand this Phillips model," says Bill Young, professor of physical oceanography at Scripps Institution of Oceanography, "The paper by Gallet and Ferrari is the first successful deductive prediction of how the heat flux in the Phillips model varies with temperature gradient."

Ferrari says that answering fundamental questions of how heat transport functions will allow scientists to more generally understand the Earth's climate system. For instance, in Earth's deep past, there were times when our planet was much warmer, when crocodiles swam in the arctic and palm trees stretched up into Canada, and also times when it was much colder and the mid-latitudes were covered in ice. "Clearly heat transfer can change across different climates, so you'd like to be able to predict it," he says. "It's been a theoretical question on the minds of people for a long time."

As the average global temperature has increased more than 1 degree Celsius in the past 100 years, and is on pace to far exceed that in the next century, the need to understand—and predict—Earth's climate system has become crucial as communities, governments, and industry adapt to the current changing environment.

"I find it extremely rewarding to apply the fundamentals of turbulent flows to such a timely issue," says Gallet, "In the long run, this physics-based approach will be key to reducing the uncertainty in climate modeling."

Following in the footsteps of meteorology giants like Norman Phillips, Jule Charney, and Peter Stone, who developed seminal climate theories at MIT, this work too adheres to an admonition from Albert Einstein: "Out of clutter, find simplicity.Study: Climate change reshaping how heat moves around globe

More information: Basile Gallet et al. The vortex gas scaling regime of baroclinic turbulence, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1916272117
Journal information: Proceedings of the National Academy of Sciences

Living under pressure: Lessons from the cradle of life

by John Hewitt , Phys.org 

Credit: JPL/NASA

Deep sea alkaline hydrothermal vents have been theorized to be a place where life could have originated. The elevated temperature, alkaline pH, and unique vent action concentrate minerals and create local energetic gradients that can promote primitive metabolic reactions. Although sometimes overlooked, the extreme hydrostatic pressures found in deep sea vents can also facilitate various kinds of molecular assembly that would not otherwise spontaneously occur at sea level.

Today, there are many complex organisms that have persisted, or otherwise re-inhabited, the deep sea through various metabolic and physiologic adaptations. Among the most extreme are the 'piezophilic' or pressure-loving prokaryotes of the Colwellia family. These organisms can be found in the deepest trenches some 11,000 meters below the surface, where pressures reach 110 megapascals (atmospheric pressure is 0.1 MPa). A recent paper published in BioRxiv analyzes the genomes of seven strains of Colwellia to find out exactly how life adapts to high pressure.

What they found was that the more piezophilic strains of Colwellia had much higher levels of basic and hydrophobic amino acids in their proteome. This would likely stabilize and limit water intrusion into proteins under pressure. The piezophilic group also had more genes for replication, recombination and repair proteins, and also for cell motility and biogenesis of the cell wall and membrane. More specifically, they had a higher percentage of unsaturated fatty acids and variant forms of cholesterol that are crucial for adjusting and maintaining membrane fluidity under high pressure.

Interestingly, many of these genes were found exclusively within highly variable regions known as genomic islands, indicating that these adaptations were likely facilitated by horizontal gene transfer through transposases or other mobile elements. One peculiarity found in these variable regions is an abundance of the rapidly modified toxin-antitoxin gene systems that are also found in many bacteria. Another observation was that the piezophilic group lacked TMAO reductase, the enzyme that reduces TMAO to TMA. This has been attributed to a preferential need for TMAO as a 'piezolyte' over its alternative use as an electron acceptor.

In looking closer at energetics and respiration, the authors identified an additional NADH ubiquinone oxidoreductase 'nuo' gene cluster in piezophiles. This unique NADH dehydrogenase translocates four protons per two electrons, and may help with energy acquisition under high pressure. Curiously, it is noted that the shewanella bacterium—now famous for its eclectic spin-dependent electron transport through multiheme electron circuits—has many similarities to Colwellia. These include not just the same kind of NADH oxidoreductases mentioned above, but also similar hypervariable toxin-antitoxin genetic systems.

High pressure can exert its effects across many different scales in living things. In general, it will alter intermolecular distances and conformations, but does not affect covalent bond lengths or bond angles. Peptides, lipids, and sugar macromolecular structures are only significantly perturbed above 2 GPa. On the other hand, protein association with DNA is less stable at elevated pressure, and the DNA double helix itself is shifted to denser forms, affecting transcription and expression.

While much of the deep sea is extremely cold, temperatures within hydrothermal vent regions can reach 400 degrees C. When combined with pressure above 30 MPa, conditions that correspond to the thermodynamic supercritical state are created. Supercritical water has an increased dielectric constant, viscosity, density and ionic hydration. As a result, the solubility of polar and ionic compounds decreases, while that of apolar molecules is enhanced. The net result of this is that prebiotic molecules are readily concentrated and can react more efficiently.

Once primitive metal-catalyzed metabolic reactions have taken hold, and amino acids are able to be polymerized into rudimentary proteins, we begin to grasp the evolution of the basic protein folds at the root of an ancient metabolic network. Such is the case for the ferredoxin fold that binds iron-sulfur compounds, and the "Rossmann" fold, which binds nucleotides. There is now evidence the two folds may have shared a common ancestor, and potentially could have been the first metabolic enzyme of life as we know it.

So why do we care about high pressure, and more importantly, what is a better understanding of it going to do for us now? For one, hyperbaric therapy has been hyped as a potential solution for many things. In fact, all the most luxurious superyachts have one below deck to decompress after a deep dive. That said, it has also been suggested as a way to bust up amyloid fibrils in Alzheimer's disease. But would that really be wise?

One potential problem is that the perplexing effect of high pressure on protein aggregation consists of, on the one hand, inducing aggregation-prone intermediate states, and on the other hand, the ability of high pressure to prevent aggregation and to dissociate aggregates. The susceptibility of protein aggregates to pressure largely depends on the degree of the structural order of an aggregate. Fresh, amorphous aggregates are more sensitive to pressure and prone to refolding to the native state than mature amyloid fibrils. Beyond Alzheimer's, these considerations may complicate other noble efforts now under review to zap infectious prion aggregates with high pressure.

Another intriguing use arises in the potential to decontaminate foods by pretreatment with high pressures. Perhaps even more timely would be the ultimate divine ability to selectively target various infectious influenza-like viruses using high pressure.Scientists have discovered the origins of the building blocks of life

---

More information: Logan M. Peoples et al. Distinctive Gene and Protein Characteristics of Extremely Piezophilic Colwellia, (2020). DOI: 10.1101/2020.03.15.992594

© 2020 Science X Network

Autism rates declining among wealthy whites, escalating among poor

by Lisa Marshall, University of Colorado at Boulder

Credit: CC0 Public Domain

Wealthy, white California counties—once considered the nation's hotbeds for autism spectrum disorder (ASD) - have seen prevalence flatten or fall in the last two decades, while rates among poor whites and minorities keep ticking up, new CU Boulder research has found.

The study, published Thursday in the Journal of Autism and Developmental Disorders, raises the possibility that parents in wealthier counties are successfully reducing environmental exposures that may contribute to autism risk, or taking other steps to curb its severity early on.

While that's a hopeful possibility, the authors say, the findings also illuminate a disturbing economic and racial divide.

"While autism was once considered a condition that occurs mainly among whites of high socioeconomic status, these data suggest that the brunt of severe autism is now increasingly being borne by low-income families and ethnic minorities," said lead author Cynthia Nevison, Ph.D., an atmospheric research scientist with the Institute of Arctic and Alpine Research, who also studies environmental health.

Adds co-author Willam Parker, Ph.D., an autism researcher at Duke University Medical Center:

"There is potentially good news here, but, unfortunately, not everyone is a beneficiary of this good news."

A shift in Silicon Valley

For the study, the researchers analyzed 20 years' worth of autism caseload counts from the California Department of Developmental Services, comparing data from 36 of the state's most populous counties.

Between birth years 1993 and 2000, autism prevalence increased steadily among all racial groups.

But around 2000, the trajectories started to diverge: Prevalence among whites in wealthy counties like Santa Clara (home to Silicon Valley) and from Monterey to the San Francisco coast started to decline.

In middle -income counties like Sacramento, Los Angeles and San Diego, prevalence among whites continued to increase, but at a slower rate.

Meanwhile, in lower income areas like Riverside and the South Central Valley, rates among whites climbed steeply.

By birth year 2013, prevalence among whites in the lowest income counties was at least double that of whites in the highest income counties. Generally speaking, the higher the county income, the lower the rate of autism among white children.

Notably, Santa Clara County had a surge in the rate of autism spectrum disorders between 1993 and 2000, with rates doubling among whites and Asians in just seven years. As Nevison and Parker recall in the new paper, that surge gave rise to controversial theories—widely reported in the media—that men with poor social skills but strong math and engineering skills were increasingly able to find partners in the tech-age and were fathering "genetically autistic" children.

"Our data contradict that argument," said Nevison, noting that today Santa Clara County has one of the lowest prevalence rates of severe autism in the state among whites. Growth in prevalence among Asians has also flattened in the county.

Meanwhile, the study found, incidence among blacks has increased rapidly across California, marking the highest rates among any ethnic or racial group at 1.8%. That finding is in line with previous research finding that autism prevalence is rising rapidly nationwide among African Americans.

Seeking answers about lowering risk

Some health experts have attributed increases in prevalence among minorities to better screening and diagnosis, but the authors believe environmental factors also play a role.

Just which factors may be at play is unclear, but Parker notes that many of the same things that fuel disease-causing inflammation—toxins, unhealthy food and emotional stress—are also associated with autism. And lower income and minority families tend to have a harder time accessing or affording healthier lifestyle options.

Established risk factors associated with autism include: advanced parental age, challenges to the immune system during pregnancy, genetic mutations, premature birth and being a twin or multiple.

The authors cannot say if their findings would translate to other counties around the country or to milder forms of autism. They also cannot rule out the possibility that wealthy families are opting out of state services in favor of private services. More research is underway.

With autism affecting one in 59 children nationwide in 2018—a rate expected to be revised by the Centers for Disease Control later this spring –they hope the paper will encourage parents and policymakers to look beyond genetics and better outreach and diagnosis.

"There is an urgent need to understand what wealthy California parents are doing or have access to that may be lowering their children's risk," they conclude.

Autism rates increasing fastest among black, Hispanic youth

---

More information: Cynthia Nevison et al. California Autism Prevalence by County and Race/Ethnicity: Declining Trends Among Wealthy Whites, Journal of Autism and Developmental Disorders (2020). DOI: 10.1007/s10803-020-04460-0

Journal information: Journal of Autism and Developmental Disorders

Private, online and hi-tech: the coronavirus economy

by India Bourke MARCH 22, 2020

Online retailers are experiencing a surge in orders from self-isolating consumers

The coronavirus pandemic has sent stock markets into freefall and industries to the wall, however many firms enabling more private, online and tech-based living are emerging as potential winners.


As hundreds of millions of people worldwide are forced to stay in their homes and not travel abroad, the businesses that are helping them to adapt could lead to long-term changes in the economy.

"I think certain aspects of work and organising will change for good through the current situation," said Sally Maitlis, a professor of organisational behaviour at Oxford University's Said Business School.

"People will discover that they can work and communicate in ways they previously didn't think possible, and will be forced to become more nimble with tech through having no choice to do otherwise."

Here are comparisons of several sectors that are thriving and failing in the pandemic:

E-commerce giants vs independent stores

Large online retailers have seen a surge in orders as self-isolating or home-working consumers turn to their massive distribution and delivery networks to provide daily essentials.

Shares in US retail giants Walmart and Amazon both tumbled as markets crashed around the world on March 16.

During the week Walmart rose as much as 25 percent from its nine-month low on Monday. Amazon also recovered.

Online retailers are experiencing a surge in orders as consumers turn to them during the coronavirus outbreak

"We are seeing increased online shopping and as a result some products such as household staples and medical supplies are out of stock," Amazon said.

Yet small, independent stores are suffering, said UK Federation of Small Businesses chair Mike Cherry.

"These are already very difficult times for all small businesses right across the country. There are huge concerns over supply chains while on top of this footfall continues to drop. The prospect for these businesses over the coming weeks is increasingly bleak."

Streaming vs cinemas

Demand for movies to watch at home has soared so much that Netflix and YouTube are reducing the quality of their streaming in Europe—which has become the epicentre of the virus—to ease pressure on the internet.


Worldwide streaming activity jumped by 20 percent last weekend, according to Bloomberg News.

Traditional cinema chains, however, are facing an unprecedented drop in demand.

India on March 12 reported its first coronavirus death as authorities ordered schools, theatres and cinemas closed in New Delhi for the rest of the month

Some have temporarily closed their doors to help contain the virus's spread.

US-listed shares in Cinemark and AMC Entertainment were both down around 60 percent on Friday from their respective highs in January and February.

Private jets vs commercial planes

The airline sector has been hit hard by quarantine rules and border closures, with UK airline Flybe crashing into bankruptcy and experts predicting others will follow.

The International Air Transport Association said Thursday that up to $200 billion is needed to rescue the global industry.

US airlines have sought more than $50 billion in government assistance in recent days, with one top US official saying the outbreak poses a bigger threat to the commercial industry than the September 11 attacks.

In contrast, private jet charter companies are seeing demand soar.

The global travel industry is one of the sectors hit hardest by the efforts to limit the novel coronavirus's spread

Wealthy customers are seeking to distance themselves from the "unknown" travel histories of fellow passengers, said Daniel Tang, from Hong Kong-based charter company MayJets.

US-based Paramount Business Jets has seen inquiries go "through the roof", its chief executive Richard Zaher said.

Queries have risen 400 percent and bookings are up 20-25 per cent.

Home workouts vs gyms

As many gyms close their doors, fitness-lovers are turning to online classes and home workouts.

Shares in US home gym equipment company Peloton surged as investors bet on increasing demand for its stationary exercise bikes and memberships to streaming online workout sessions.

At one stage Peloton's share price was up more than 50 percent from Monday's intra-day low.

Teleconferences vs real world meetings

With more and more people working from home to limit the virus's spread, demand for technology that enables online group meetings, chats and collaborations has spiked.

Graphic naming selected companies that could benefit from the "coronavirus economy,' according to a Forbes data from March 7

"There is such excitement around remote work that brands like Zoom have seen their stock value climb up," Creative Strategies analyst Carolina Milanesi said, referring to the teleconferencing app.

At the same time, real world gatherings from sporting events to business conferences, have been postponed or cancelled, with a large question mark still lingering over the fate of this summer's Olympic Games in Japan.

Crowdsourced virtual supercomputer revs up virus research
by Rob Lever

A crowdsourcing project drawing on individual and corporate computing power worldwide has created a supercomputer to help accelerate coronavirus research

Gamers, bitcoin "miners" and companies large and small have teamed up for an unprecedented data-crunching effort that aims to harness idle computing power to accelerate research for a coronavirus treatment.


The project led by computational biologists has effectively created the world's most powerful supercomputer that can handle trillions of calculations needed to understand the structure of the virus.

More than 400,000 users downloaded the application in the past two weeks from "Folding@Home," according to director Greg Bowman, a professor of biochemistry and molecular biophysics at Washington University in St. Louis, where the project is based.

The "distributed computing" effort ties together thousands of devices to create a virtual supercomputer.

The project originally launched at Stanford University 20 years ago was designed to use crowdsourced computing power for simulations to better understand diseases, especially "protein folding" anomalies that can make pathogens deadly.

"The simulations allow us to watch how every atom moves throughout time," Bowman told AFP.

The massive analysis looks for "pockets" or holes in the virus where a drug can be squeezed in.

"Our primary objective is to hunt for binding sites for therapeutics," Bowman said.

A crowdsourced computing project aims to find pockets or "holes" in the coronavirus which can be attacked with drugs

'Druggable targets'

The powerful computing effort can test potential drug therapies, a technique known as computational drug design.

Bowman said he is optimistic about this effort because the team previously found a "druggable" target in the Ebola virus and because COVID-19 is structurally similar to the SARS virus which has been the subject of many studies.

"The best opportunity for the near-term future is if we can find an existing drug that can bind to one of these sites," he said.

"If that happens it could be used right away."

This is likely to include drugs like the antimalarials chloroquine and hydroxychloroquine which may be "repurposed" for COVID-19.

Bowman said the project has been able to boost its power to some 400 petaflops—with each petaflop having a capacity to carry out one quadrillion calculations per second—or three times more powerful than the world's top supercomputers.

Other supercomputers are also working in parallel. The Oak Ridge National Laboratory said earlier this month that by using IBM's most powerful supercomputer it had identified 77 potential compounds that could bind to the main "spike" protein of the coronavirus to disarm the pathogen.

Researchers using powerful computer analysis are seeking to better understand the molecular structure of COVID-19 to help find a treatment

'No end' to compute power


The Folding@Home project is fueled by crowdsourced computing power from people's desktops, laptops and even PlayStation consoles, as well as more powerful business computers and servers.

"There is no end to the compute power than we can use in principle," Bowman said. Large tech firms including Microsoft-owned GitHub are also participating, and the project is in discussions with others.

Anyone with a relatively recent computer can contribute by installing a program which downloads a small amount of data for analysis. People can choose which disease they wish to work on.

"It's like bitcoin mining, but in the service of humanity," said Quentin Rhoads-Herrera of the security firm Critical Start, which has provided its powerful password "hash cracker" computer designed to decrypt passwords to the project.

Rhoads-Herrera said his team of security researchers, sometimes described as "white hat hackers," were encouraging more people to get involved.

Chipmaking giant Nvidia has urged gamers to join the crowdsourced computing effort by donating idle computing time on their powerful gaming computers

Fighting helplessness

Computer chipmaker Nvidia, which makes powerful graphics processors for gaming devices, called on gamers to join the effort as well.

"The response has been record-breaking, with tens of thousands of new users," joining, said Nvidia spokesman Hector Marinez.

One of the largest contributions comes from a Reddit group of PC enthusiasts and gamers which has some 24,000 members participating.

"It is a fantastic weapon against the feeling of helplessness," said Pedro Valadas, a lawyer in Portugal who heads the Reddit community and is a part of the project's advisory board.

"The fact that anyone, at home, with a computer, can play a role and help fight against (disease) for the common good is a powerful statement," Valadas told AFP.
Crowd-sourced computer network delves into protein structure, seeks new disease therapies

© 2020 AFP

Impact of a second Dust Bowl would be felt worldwide

by Frontiers

Credit: CC0 Public Domain

The American Dust Bowl of the 1930s—captured by the novels of John Steinbeck—was an environmental and socio-economic disaster that worsened the Great Depression.

The Dust Bowl was an extreme event. But due to climate change, massive crop failures are more likely to happen again in the future. New research in Frontiers in Sustainable Food Systems aimed to answer what these impacts may look like.

The Dust Bowl was centered on the Great Plains of the USA, where decades of unsustainable deep plowing had displaced native, moisture-retaining grasses. An atypical La Niña then brought intense droughts, high temperatures, and strong winds which blew away the topsoil in the form of large-scale dust storms.

Apart from its direct impact on people (around 7,000 deaths and two million homeless), the Dust Bowl had a catastrophic effect on crops where wheat and maize production in the USA plummeted by 36% and 48% during the 1930s.

Currently, the Intergovernmental Panel on Climate Change predicts that in another three to four decades that most of the USA will have further warmed by 1.5-2 °C. This compounds issues that already exist today, where global food security is under pressure from the increased frequency of extreme weather events.

"We wanted to forecast how a multi-year production decline in a major exporting country, similar to that which occurred during the Dust Bowl, would affect modern food supplies globally via international trade," says first author Dr. Alison Heslin, a postdoctoral researcher at the Center for Climate Systems Research of Columbia University and NASA's Goddard Institute for Space Studies.

"In today's system of global food trade, disruptions are not bound by borders. Shocks to production are expected to affect trade partners who depend on imports for their domestic food supply."

To assess the possible impacts of a second dust bowl, the authors first developed two alternative computer simulations of the worldwide trade in wheat. They then delivered a shock to these model systems in the form of a four-year-long Dust Bowl-like anomaly, restricted to the USA.

Under one simulation, countries first use their reserves and then divide the absorbed shock between imports and exports, propagating it in one direction by increasing imports and in another by decreasing exports.

Under the more complicated second model, the USA first reduces only its exports, propagating the shock to all receiving trade partners, after which all countries with a shortage respond by increasing their imports.

Their results predict a severity similar to that of the original event, estimated from historical data. The results show that the USA would fully exhaust 94% of its reserves over the first four years of a Dust Bowl-liked agricultural shock.

They also show that without exception, all countries to which the USA exports wheat would decrease their reserves, even though they didn't themselves suffer crop failure.

"We focused on a subset of the possible impacts, specifically changes in trade, drawing down strategic reserves and decreases in consumption," says co-author Dr. Jessica Gephart, Assistant Professor at the Department of Environmental Science of the American University in Washington DC.

"We found that global wheat trade contracts and shifts toward other wheat exporters, and that wheat reserves around the world decline, in many cases to zero. This suggests that the impacts would not only raise prices for US consumers but would also raise prices far beyond the US borders," says Gephart.

Key impacts of another four-year dust bowl could include an initial 31% loss of global wheat stocks, and by the end of the four years, between 36-52 countries could have used up over 75% of their starting reserves. The 10 countries with the highest initial reserves (China, USA, India, Iran, Canada, Russia, Morocco, Australia, Egypt, Algeria) would see their reserves decline by 15-22 % relative to the starting points.

However, a silver lining is that due to the high initial starting point of global reserves, most supply shocks, even in countries without reserves, could be addressed through trade flow adjustments without reducing consumption.

"Our results remind us that mitigating climate risks requires accounting for not only the direct effects of climate change, like local extreme weather events, but also the climate impacts which travel through our interconnected system of global trade."

"In the context of food security, we show that accessing food reserves can, for a time, buffer populations from trade-induced supply shortages but as reserves deplete, people are at risk of food shortages," says Heslin.

Climate change and the threat to global breadbaskets

---

More information: Frontiers in Sustainable Food Systems, DOI: 10.3389/fsufs.2020.00026 , https://www.frontiersin.org/articles/10.3389/fsufs.2020.00026/full

Hidden source of carbon found at the Arctic coast

by University of Texas at Austin 

Credit: CC0 Public Domain

A previously unknown significant source of carbon just discovered in the Arctic has scientists marveling at a once overlooked contributor to local coastal ecosystems—and concerned about what it may mean in an era of climate change.

In a Nature Communications paper released today, aquatic chemists and hydrologists from The University of Texas at Austin's Marine Science Institute and Jackson School of Geosciences, U.S. Fish and Wildlife Service and Florida State University present evidence of significant, undetected concentrations and fluxes of dissolved organic matter entering Arctic coastal waters, with the source being groundwater flow atop of frozen permafrost. This water moves from land to sea unseen, but researchers now believe it carries significant concentrations of carbon and other nutrients to Arctic coastal food webs.

Groundwater is known globally to be important for delivering carbon and other nutrients to oceans, but in the Arctic, where much water remains trapped in frozen earth, its role has been less clear. Scientists were surprised to learn that groundwater may be contributing an amount of dissolved organic matter to the Alaskan Beaufort Sea that is almost on a par with what comes from neighboring rivers during the summer.

"We have to start thinking differently about groundwater," said senior author Jim McClelland, professor of marine sciences at UT Austin. "The water that flows from rivers to the Arctic Ocean is pretty well accounted for, but until now the groundwater flowing to this ocean hasn't been."

The research community has generally assumed that groundwater inputs from land to sea are small in the Arctic because perennially frozen ground, or permafrost, constrains the flow of water below the tundra surface.

The research published today describes sampling the concentration and age of dissolved carbon, as well as nitrogen, in groundwater flowing beneath the land's surface in the Arctic during the summer. The team found that as shallow groundwater flows beneath the surface at sites in northern Alaska, it picks up new, young organic carbon and nitrogen as expected. However, they also discovered that as groundwater flows toward the ocean, it mixes with layers of deeper soils and thawing permafrost, picking up and transporting century-to-millennia old organic carbon and nitrogen.

This old carbon being transported by groundwater is thought to be minimally decomposed, never having seen the light of day before it meets the ocean.

"Groundwater inputs are unique because this material is a direct shot to the ocean without seeing or being photodegraded by light," McClelland said. "Sunlight on the water can decompose organic carbon as it travels downstream in rivers. Organic matter delivered to the coastal ocean in groundwater is not subject to this process, and thus may be valuable as a food source to bacteria and higher organisms that live in Arctic coastal waters."

The researchers concluded that the supply of leachable organic carbon from groundwater amounts to as much as 70% of the dissolved organic matter flux from rivers to the Alaska Beaufort Sea during the summer.

"Despite its ancient age, dissolved organic carbon in groundwater provides a new and potentially important source of fuel and energy for local coastal food webs each summer," said lead author Craig Connolly, a recent graduate of UT Austin's Marine Science Institute. "The role that groundwater inputs play in carbon and nutrient cycling in Arctic coastal ecosystems, now and in the future as climate changes and permafrost continues to thaw, is something we hope will spark research interest for years to come."

Co-author M. Bayani Cardenas, a professor in the Jackson School of Geosciences, said that climate change's outsized effect on the Arctic makes groundwater research all the more important.

"The Arctic is heating up twice as much as the rest of the planet. With that comes permafrost thawing and the birth of aquifers," he said. "It is likely that groundwater transport in the Arctic will be more and more important in the future."

Fresh groundwater flow important for coastal ecosystems

---

More information: Nature Communications (2020). DOI: 10.1038/s41467-020-15250-8