A local ornithological expert conducted regular bird surveys over one year and recorded 126 bird species. Using remote sensing techniques, satellite pictures were processed to produce a map of different land-uses, from which urbanization intensity was measured based on the proportion of sealed surfaces and buildings in the landscape. The researchers analyzed how farmland bird communities changed along a gradient of urbanization using newly developed statistical analyses.

“We found that urban bird communities were impoverished subsets of rural communities, both in terms of species composition and the ecological functions they provide,” says first author Gabriel Marcacci, PhD student in the Functional Agrobiodiversity group at the University of Göttingen. “Birds perform important roles in the environment, for instance controlling pests by eating insects, scavenging and removing carrion, or eating fruits and dispersing the seeds. But only bird species that are well adapted to urban environments such as pigeons or crows can thrive.”

“The homogenization — resulting from losing diversity through the exclusion of certain groups — of farmland bird communities may disrupt important ecosystem functions and services in urban agroecosystems such as pest removal by insect-eating birds,” explains Professor Catrin Westphal, head of the Functional Agrobiodiversity group. Urban communities were found to be more sensitive to species loss, endangering ecosystem resilience.

“Our study underscores urbanization as a serious threat to biological communities and ecosystem functioning that may affect food production systems,” adds Professor Ingo Graß, head of the Department of Ecology of Tropical Agricultural Systems at the University of Hohenheim. Professor Teja Tscharntke concludes, “This concern is especially relevant for countries from the Global South where urban agriculture and ecosystem services play an increasingly important role for food security.”

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“We wanted to establish a way to build scaled wood-frame specimens that would behave, and ultimately fail, under wave loading like their full-scale counterparts have been observed to,” said Sean Duncan, who led the study as a graduate research assistant with the Oregon State College of Engineering. “And we also set out to develop an equation that could predict the distribution of the uplift pressure on elevated structures. We were able to accomplish both of those goals.”

One of the model structures was elevated — built so that the living areas would be off the ground — and the other was “on grade,” or on the ground. As the researchers expected, the on-grade model couldn’t withstand water levels as high as the raised one, and both sustained damage in ways consistent with what was seen in real residential structures during Hurricane Sandy in 2012 and Hurricane Ike in 2008.

The research by Duncan, OSU colleagues Dan Cox, Andre Barbosa and Pedro Lomonaco and collaborators from the University of Hawaii and the University of California, Berkeley, also showed that a remote sensing method known as LiDAR could track the models’ damage progression as the waves and storm surges increased in intensity.

The models were built to one-sixth scale, with strength and stiffness on par with real residences such as those hit by Hurricane Sandy in Ortley Beach, New Jersey, and by Hurricane Ike on Texas’ Bolivar Peninsula. Each of those storms caused extensive damage, which focused greater attention on coastal communities’ vulnerability to waves and storm surges, and on learning more about how to design and construct storm-resistant homes, Duncan said.

“Populations in those types of communities are rising, and so are sea levels,” said Duncan, now a ports and marine engineer with WSP USA in Federal Way, Washington. “That means risk associated with hurricanes is rising too, especially because research indicates hurricanes are increasing in intensity and will continue to do so. That’s why it’s so important to understand the forces these storms generate and how coastal structures respond, so planners and the construction industry can work together to mitigate the potential damage from these very likely, very potent storms.”

Placed on a simulated coastline in the Directional Wave Basin at the O.H. Hinsdale Wave Research Laboratory, the models experienced waves and water depths replicating conditions of Hurricane Sandy. The basin is 48.8 meters long, 26.5 meters wide and just over 2 meters deep, and multiple instruments measured the hydrodynamic loads.

Vertical forces on the elevated specimen were shown to correlate with wave height, air gap and water depth, Duncan said, with the forces peaking in the deepest water at maximum submergence.

“Uplift pressure is also affected by how and where the waves break,” he said. “Waves that broke right on the specimens generally caused bigger vertical forces. And the predictive equation we developed, based on wave height and air gap, is valid for a range of structure length to wavelength ratios, wave heights, air gaps and water depths.”

Air gap refers to the elevation of the bottom of the lowest horizontal member, or LHM, of an elevated structure relative to the still water level.

Findings were published in Coastal Engineering, and the research was supported by Department of Homeland Security and the National Science Foundation.

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The achievement could facilitate the development of superfast quantum computers and energy-efficient superconductors.

The scientists are the first to capture an image of how electrons in a QSL decompose into spin-like particles called spinons and charge-like particles called chargons.

“Other studies have seen various footprints of this phenomenon, but we have an actual picture of the state in which the spinon lives. This is something new,” said study leader Mike Crommie, a senior faculty scientist at Lawrence Berkeley National Laboratory (Berkeley Lab) and physics professor at UC.

“Spinons are like ghost particles. They are like the Big Foot of quantum physics — people say that they’ve seen them, but it’s hard to prove that they exist,” said co-author Sung-Kwan Mo, a staff scientist at Berkeley Lab’s Advanced Light Source. “With our method we’ve provided some of the best evidence to date.”

A surprise catch from a quantum wave

In a QSL, spinons freely move about carrying heat and spin — but no electrical charge. To detect them, most researchers have relied on techniques that look for their heat signatures.

Now, as reported in the journal Nature Physics, Crommie, Mo, and their research teams have demonstrated how to characterize spinons in QSLs by directly imaging how they are distributed in a material.

To begin the study, Mo’s group at Berkeley Lab’s Advanced Light Source (ALS) grew single-layer samples of tantalum diselenide (1T-TaSe₂) that are only three-atoms thick. This material is part of a class of materials called transition metal dichalcogenides (TMDCs). The researchers in Mo’s team are experts in molecular beam epitaxy, a technique for synthesizing atomically thin TMDC crystals from their constituent elements.

Mo’s team then characterized the thin films through angle-resolved photoemission spectroscopy, a technique that uses X-rays generated at the ALS.

Using a microscopy technique called scanning tunneling microscopy (STM), researchers in the Crommie lab — including co-first authors Wei Ruan, a postdoctoral fellow at the time, and Yi Chen, then a UC Berkeley graduate student — injected electrons from a metal needle into the tantalum diselenide TMDC sample.

Images gathered by scanning tunneling spectroscopy (STS) — an imaging technique that measures how particles arrange themselves at a particular energy — revealed something quite unexpected: a layer of mysterious waves having wavelengths larger than one nanometer (1 billionth of a meter) blanketing the material’s surface.

“The long wavelengths we saw didn’t correspond to any known behavior of the crystal,” Crommie said. “We scratched our heads for a long time. What could cause such long wavelength modulations in the crystal? We ruled out the conventional explanations one by one. Little did we know that this was the signature of spinon ghost particles.”

How spinons take flight while chargons stand still

With help from a theoretical collaborator at MIT, the researchers realized that when an electron is injected into a QSL from the tip of an STM, it breaks apart into two different particles inside the QSL — spinons (also known as ghost particles) and chargons. This is due to the peculiar way in which spin and charge in a QSL collectively interact with each other. The spinon ghost particles end up separately carrying the spin while the chargons separately bear the electrical charge.

In the current study, STM/STS images show that the chargons freeze in place, forming what scientists call a star-of-David charge-density-wave. Meanwhile, the spinons undergo an “out-of-body experience” as they separate from the immobilized chargons and move freely through the material, Crommie said. “This is unusual since in a conventional material, electrons carry both the spin and charge combined into one particle as they move about,” he explained. “They don’t usually break apart in this funny way.”

Crommie added that QSLs might one day form the basis of robust quantum bits (qubits) used for quantum computing. In conventional computing a bit encodes information either as a zero or a one, but a qubit can hold both zero and one at the same time, thus potentially speeding up certain types of calculations. Understanding how spinons and chargons behave in QSLs could help advance research in this area of next-gen computing.

Another motivation for understanding the inner workings of QSLs is that they have been predicted to be a precursor to exotic superconductivity. Crommie plans to test that prediction with Mo’s help at the ALS.

“Part of the beauty of this topic is that all the complex interactions within a QSL somehow combine to form a simple ghost particle that just bounces around inside the crystal,” he said. “Seeing this behavior was pretty surprising, especially since we weren’t even looking for it.”

The findings, published in the journal in the American Journal of Primatology, help to increase the understanding of how climate change impacts biodiversity, and how to mitigate against predicted biodiversity loss in the future. This research was led by the German Centre for Integrative Biodiversity Research (iDiv), the Max Planck Institute for Evolutionary Anthropology, and an international team of over 80 collaborators from research institutes across the globe.

For their analysis, the authors compiled over 130,000 occurrence records of chimpanzees stored in the A.P.E.S. database of the International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC), as well as data from the Pan African Programme: The Cultured Chimpanzee (PanAf) at the MPI-EVA and iDiv, Leipzig.The researchers quantified chimpanzee habitat suitability using species distribution models based on chimpanzee occurrences, climate and human density data, and then projected these models onto temporal snapshots of climate reconstructions at up to 1000 year intervals, dating back to the Last Interglacial period (120,000 years ago). For the first time, they were able to build a dynamic model of habitat suitability over time, permitting long-term stability (i.e. glacial refugia) to be calculated.

Results show that glacial refugia across Africa may have been underestimated for chimpanzees, with potentially up to 60,000 additional square kilometers (23,166 square miles) in the Upper and Lower Guinea Forests in West and Central Africa, and the Albertine Rift in East Africa.

In addition, results provide explicit insights into chimpanzee habitat and how it may have shifted throughout time, enabling hypotheses of how global change has affected genetic and behavioral diversity to be tested in the future.

Said lead author of the study Chris Barratt, a postdoctoral researcher at iDiv: “By integrating past climate and human density estimates, as well as species richness of keystone tropical plants (figs and palms), this study provides strong evidence of glacial refugia for chimpanzees being geographically larger than previously thought. It may well be that some of these refugia deserve greater levels of protection than they currently receive as they are important for the persistence of populations and species during periods of global change.”

The results provide a new resource for understanding patterns of genetic and behavioral diversity in chimpanzees. Chimpanzees exhibit highly differentiated genetic diversity (for example, lower in West Africa and higher in East and Central Africa), as well as high levels of behavioral differentiation based on the environmental variability they are exposed to, including Pleistocene forest refugia.

Said Hjalmar Kühl at iDiv, and senior author of the study: “We are only beginning to understand how past environmental changes have influenced the diversity in great apes we find today. A better understanding of these processes will tell us when variable environments serve as engines of diversification and when not. In the end these insights into great apes will also offer insights into our own evolution.”

Said Fiona Maisels of the Wildlife Conservation Society and a co-author of the study: “To effectively conserve chimpanzees (and other species) over the centuries to come, it is essential to understand the past. Humans are changing the planet’s climate and its habitats ever more rapidly. Approaches such as those used in this study are vital for predicting how these changes will affect future wildlife abundance and distribution, and to ensure space and safety for a multitude of species.”

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In a study published August 23 in Nature Ecology and Evolution Harvard researchers establish the origin date of the earliest tetrapods and discover they acquired several of the major new adaptive traits that enabled vertebrate life on land at accelerated evolutionary rates.

The study led by Dr. Tiago R. Simões, postdoctoral researcher, and senior author Professor Stephanie E. Pierce, both from the Department of Organismic and Evolutionary Biology, Harvard University, applied recently developed statistical methods (Bayesian evolutionary analysis) to precisely estimate the time and rates of anatomical evolution during the rise of tetrapods. The Bayesian method was adapted from methods originally developed in epidemiology to study how viruses like COVID-19 evolve and only recently became a tool in paleontology for the study of species evolution.

The study also innovates by combining data from fossil footprints and body fossils to pinpoint the time of origin of the tetrapods. “Normally footprint data shows up after body fossils of their track makers. In this case, we have tetrapod footprints much older than the first body fossils by several million years, which is extremely unusual. By combining both footprint and body fossils, we could search for a more precise age for the rise of tetrapods,” said Pierce.

“We were able to provide a very precise age for the origin of tetrapods at approximately 390 million years ago, 15 million years older than the oldest tetrapod body fossil,” said Simões.

The researchers also found that most of the close relatives to tetrapods had exceptionally slow rates of anatomical evolution, suggesting the fish relatives to tetrapods were quite well adapted to their aquatic lifestyle.

“On the other hand, we discovered the evolutionary lineages leading to the first tetrapods broke away from that stable pattern, acquiring several of the major new adaptive traits at incredibly fast rates that were sustained for approximately 30 million years,” said Simões.

Simões and Pierce also extended molecular approaches to study how fast different parts of the early tetrapod body plan evolved — such as the skull, jaws, and limbs — and the strength of natural selection acting on each of them. They found that all parts of the tetrapod skeleton were under strong directional selection to evolve new adaptive features, but that the skull and jaws were evolving faster than the rest of the body, including the limbs.

“This suggest that changes in the skull had a stronger role in the initial stages of the fish-to-tetrapod transition than changes in the rest of the skeleton. The evolution of limbs to life on land was important, but mostly at a later stage in tetrapod evolution, when they became more terrestrial,” said Pierce.

“We see several anatomical innovations in their skull related to feeding and food procurement, enabling a transition from a fish-like suction-based mode of prey capture to tetrapod-like biting, and an increase in orbit size and location” said Simões. “These changes prepared tetrapods to look for food on land and to explore new food resources not available to their fish relatives.”

The researchers also found that the fast rates of anatomical evolution in the tetrapod lineage were not associated with fast rates of species diversification. In fact, there were very few species around, so few they had a very low probability of being preserved in the fossil record.

This finding helps to answer an ongoing debate in evolution of whether new major animal groups originated under fast rates of anatomical change and species diversification (the classical hypothesis). Or, if there were high rates of anatomical evolution first, with increased rates of species diversification occurring only several million years later (a new hypothesis).

“What we’ve been finding in the last couple of years is that you have lots of anatomical changes during the construction of new animal body plans at short periods of geological time, generating high rates of anatomical evolution, like we’re seeing with the first tetrapods. But in terms of number of species, they remained constrained and at really low numbers for a really long time, and only after tens of millions of years do they actually diversify and become higher in number of species. There’s definitely a decoupling there,” said Simões.

Pierce agreed, “It takes time to get a foothold in a new niche in order to take full advantage of it.”

“Our study starts at the very beginning of this evolutionary story. There are many, many more chapters to come,” said Pierce. “We want to next dig further in terms of what happened after the origin of tetrapods, when they started to colonize land and diversify into new niches. How does that impact their anatomical rates of evolution compared to their species diversification across the planet? This is just the very beginning. It’s the introductory chapter to the book.”

The study, published August 23, 2021, was led by Nicole Tichenor Blackstone in the Agriculture, Food and Environment program at the Friedman School of Nutrition Science & Policy at Tufts, and Jessica Decker Sparks, who leads the Ecosystems and the Environment Programme at the University of Nottingham Rights Lab.

“Sustainability research on the food supply typically focuses on promoting human health and protecting the environment,” said first and corresponding author Blackstone. “But social sustainability provides a different perspective on our food sources, including issues of labor rights and equity. Globally, agriculture has one of the highest incidences of forced labor.”

The study developed a new forced labor risk scoring method that draws upon original data compiled by the authors as well as a range of governmental and non-profit data. The research team then coded each food and country-of-origin combination as either very high risk, high risk, medium risk, or low risk for forced labor having occurred at some point in the growing and harvesting of each item. Previously, there have been short lists of commodities suspected of being produced with forced labor, or case studies of foods produced in one country, such as Mexico.

“What we’ve done, for the first time, is to look at all of the major fruits and vegetables consumed in the U.S., as well as all of the countries these foods come from, including the U.S., and assess the possibility that somewhere in the production process forced labor could have been involved,” said Blackstone.

The scoring method is not meant to be a consumer tool but could help industry and policy makers interested in the development of systems and protocols for the responsible procurement of foods.

The final data set included 93 fruits and vegetables in 307 food-country combinations. The results of the qualitative coding show that most food-country combinations were coded as high risk (85%) for forced labor at some point. Seven percent were coded as very-high risk, 4.5% were coded as medium risk, and 3.5% were coded as low risk.

“This is an extraordinary percentage at high risk, but it reflects that there are very limited or coarse data,” said senior author Sparks. “There are major structural issues with how agricultural labor is set up that make workers vulnerable. To us, this reflects systemic issues in food supply chains that have not been addressed. Our findings point to the need for policymakers, farmers, and food companies to engage with farm workers to address the systemic issues.”

Some of the variables that factored into the scoring were:

• documented history of forced labor for a given food in a given country;
• a country’s record on monitoring forced labor — a good record lowered the score and vice versa; and,
• whether a given food is harvested by hand or by machine.

Agricultural work often takes place in remote and isolated environments with demanding labor requirements. There are typically inadequate legal protections, with piece-rate pay systems tied to productivity, and reliance on migrant labor.

As defined by the International Labour Organization, “forced labour can be understood as work that is performed involuntarily and under the menace of any penalty. It refers to situations in which persons are coerced to work through the use of violence or intimidation, or by more subtle means such as manipulated debt, retention of identity papers or threats of denunciation to immigration authorities.”

“Forced labor in agriculture is a threat to the sustainability of food systems. However, the scarcity of data noted limits holistic analysis and action. Future research should prioritize data and model development to enable analyses of forced labor and other labor-related social risks (e.g., wages, child labor) across the life cycles of a wide range of foods. These efforts can help ensure that the rights and dignity of “the hands that feed us” are centered in the transformation of food systems,” concluded the authors in the study.

Authors and Funding

Additional authors of the study are Catherine Benoit Norris of NewEarth B, Bethany Jackson of the Rights Lab and School of Geography at the University of Nottingham, and Tali Robbins, who was a master’s degree student at the Friedman School at the time of the study.

Jessica Decker Sparks was supported by the Nottingham Research Fellowship, University of Nottingham, and Tali Robbins was supported by the Friedman School. Please see the study for conflicts of interest.