Genetic enigma solved

Inheritance of coat color patterns in dogs

Peer-Reviewed Publication

UNIVERSITY OF BERN

 

IMAGE: TIBETAN WOLVES AT THE PADMAJA NAIDU HIMALAYAN ZOOLOGICAL PARK, DARJEELING. THEIR COAT COLOR IS SHADED YELLOW. view more 

CREDIT: S. SHANKAR

The inheritance of several coat color patterns in dogs has been controversially debated for decades. Researchers including Tosso Leeb from the Institute of Genetics of the University of Bern have now finally been able to solve the puzzle. Not only did they clarify how the coat color patterns are genetically controlled, but the researchers also discovered that the light coat color in white arctic wolves and many modern dogs is due to a genetic variant originating in a species that went extinct a long time ago. The study has just been published in the scientific journal Nature Ecology and Evolution.

Two pigments and a "switch" for all coat colors

Wolves and dogs can make two different types of pigment, the black one, called eumelanin and the yellow, pheomelanin. A precisely regulated production of these two pigments at the right time and at the right place on the body gives rise to very different coat color patterns. Prior to the study, four different patterns had been recognized in dogs and several genetic variants had been theorized which cause these patterns. However, commercial genetic testing of these variants in many thousands of dogs yielded conflicting results, indicating that the existing knowledge on the inheritance of coat color patterns was incomplete and not entirely correct.

During the formation of coat color, the so-called agouti signaling protein represents the body's main switch for the production of yellow pheomelanin. If the agouti signaling protein is present, the pigment producing cells will synthesize yellow pheomelanin. If no agouti signaling protein is present, black eumelanin will be formed. "We realized early on that the causative genetic variants have to be regulatory variants which modulate the rate of protein production and lead to higher or lower amounts of agouti signal protein", Tosso Leeb explains.

CAPTION

Five different color patterns in dogs controlled by promoter variants at the gene for agouti signaling protein. The activity of the ventral promoter (VP) or the hair cycle specific promoter (HP) is schematically indicated under each dog.

CREDIT

NEE / Tosso Leeb

Five instead of four distinct coat color patterns

The gene for agouti signaling protein has several initiation sites for reading the genetic information, which are called promoters. Dogs, on the one hand, have a ventral promoter, which is responsible for the production of agouti signaling protein at the belly. On the other hand, dogs have an additional hair cycle-specific promoter that mediates the production of agouti signaling protein during specific stages of hair growth and enables the formation of banded hair.

For the first time, the researchers characterized these two promoters in detail, in hundreds of dogs. They discovered two variants of the ventral promoter. One of the variants conveys the production of normal amounts of agouti signaling protein. The other variant has higher activity and causes the production of an increased amount of agouti signaling protein. The researchers even identified three different variants of the hair cycle-specific promoter. Starting with these variants at the individual promoters, the researchers identified a total of five different combinations, which cause different coat color patterns in dogs. "The textbooks have to be rewritten as there are five instead of the previously accepted four different patterns in dogs", Leeb says.

CAPTION

Arctic Wolf (Canis lupus arctos) in the Lüneburg Heath wildlife park, Germany. The white coat color is caused by the same genetic variant that leads to the dominant yellow color in dogs.

CREDIT

Quartl

Unexpected insights on the evolution of wolves

As many genomes from wolves of different regions on earth have become publicly available, the researchers further investigated whether the identified genetic variants also exist in wolves. These analyses demonstrated that the variants for overactive ventral and hair cycle-specific promoters were already present in wolves prior to the domestication of modern dogs, which started approximately 40,000 years ago. Most likely, these genetic variants facilitated adaptation of wolves with a lighter coat color to snow-rich environments during past ice ages. Today, the completely white arctic wolves and the light colored wolves in the Himalaya still carry these genetic variants.

Further comparisons of the gene sequences with other species of the canidae family yielded very surprising results. The researchers were able to show that the overactive variant of the hair cycle-specific promoter in light-colored dogs and wolves shared more similarities with very distantly related species such as the golden jackal or the coyote than with the European grey wolf.

"The only plausible explanation for this unexpected finding is an ancient origin of this variant, more than two million years ago, in a now extinct relative of wolves", Leeb says. The gene segment must have been introgressed more than two million years ago into wolves by hybridization events with this now extinct relative of wolves. Thus, a small piece of DNA from this extinct species is still found today in yellow dogs and white arctic wolves. "This is reminiscent of the spectacular finding that modern humans carry a small proportion of DNA in their genomes from the now extinct Neandertals", Leeb adds.

CAPTION

Eurasian grey wolf at Polar Zoo in Bardu, Norway, with the coat color agouti.

CREDIT

Mas3cf

International collaboration was key to success

The study was enabled by a sabbatical done by Prof. Danika Bannasch at the University of Bern with its longstanding research focus on the genetics of coat color in domestic animals. Bannasch, a professor in veterinary genetics at the University of California Davis, filtered the relevant promoter variants from thousands of other functionally neutral genetic variants. The evolutionary analyses were conducted by Christopher Kaelin und Gregory Barsh of the HudsonAlpha Institute and Standford University.

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JOURNAL

Nature Ecology & Evolution

DOI

10.1038/s41559-021-01524-x

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Dog colour patterns explained by modular promoters of ancient canid origin

ARTICLE PUBLICATION DATE

11-Aug-2021

Tree falls during dry season in São Paulo City are due to poor management, study suggests

An article in Trees - Structure and Function reports findings from an analysis of 7,000 tree falls in a three-year period. Stormy weather was the main cause during the rainy season.

Peer-Reviewed Publication

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

 

IMAGE: STORMY WEATHER WAS THE MAIN CAUSE DURING THE RAINY SEASON view more 

CREDIT: PRISCILLA CERQUEIRA

Trees fall every day in São Paulo, Brazil, the largest and most populous city in Latin America, but most tree falls occur in the rainy season owing mainly to the effects of temperature, strong winds and heavy rain. When trees fall in the dry season, the main direct cause is not weather but a lack of management and adequate conditions for the survival of street vegetation.

These are the key findings of a study published by a group of Brazilian researchers in the journal Trees - Structure and Function as part of its “Urban Trees” collection. The study was supported by FAPESP via two projects (19/08783-0 and 20/09251-0).

The scientists analyzed daily tree fall data and identified some 7,000 occurrences in three years. São Paulo lost 1% of its street trees in the period, for an average of 6.2 falls per day. The worst day was December 29, 2014, when 337 tree falls were reported in 24 hours. Ibirapuera Park, the city’s largest green area, had to be closed because of the number of trees blown down in the storm.

Trees are considered crucial to maintaining or improving environmental quality in cities. They play an important role in carbon storage and uptake, helping mitigate the adverse effects of global warming and pollution. They also help reduce flooding by increasing the more permeable soil area and reducing the speed and volume of stormwater runoff by intercepting part of the rain.

“Out of São Paulo’s 652,000 street trees, 7,034 fell in the period 2013-16. Our analysis showed that tree fall is driven by precipitation, wind gust and temperature during the wet season. While temperature directly influences tree fall, both precipitation and wind gust may have lagged effects, leading to tree fall some days after the weather event. However, such associations with climate were not observed during the dry season, although trees fell on two-thirds of the days in the season, confirming problems due to poor stewardship and conditions,” the article can be summarized as concluding.

The data used in the study came from the City of São Paulo’s Center for Emergency Management. The exact location of each tree fall was not available. The researchers focused on correlations between daily weather and tree falls, estimating immediate effects and the impact of rain and wind a few days after a storm.

“When rainfall is heavy, trees retain much more water and their weight increases. In addition, large amounts of water in the ground reduce soil-root friction, making a fall more likely. If the soil is waterlogged, however, the increase in soil weight offsets the loss of friction, and the tree may not fall during heavy rain. As the soil dries out, its weight decreases without any increase in friction, and it may fall,” Giuliano Locosselli, a researcher at IB-USP’s Department of Botany and first author of the article, told Agência FAPESP.

The co-authors included Marcos Silveira Buckeridge, a professor at the University of São Paulo’s Institute of Biosciences (IB-USP), and Priscilla Cerqueira, an agricultural engineer and head of the Urban Tree Division of the City of São Paulo’s Department of the Environment.

According to Locosselli, the results show that the effects of climate are concentrated in the rainy season. “Trees fall apparently without climate-related causes during the dry season, evidencing lack of care and structural problems that have been occurring for some time,” he said.

For example, trees are pruned incorrectly, weakening their structure or balance, sidewalks strangle their roots or hinder their development, and there is often insufficient room for them to grow.

“Poorly managed trees are likely to fall even without apparent climate-related causes. Senescent vegetation can fall owing to impairment of photosynthesis, root support, growth and resistance to pathogens, which take advantage of the urban climate to reproduce and develop. It’s not unusual to find trees in poor conditions that can fall for no apparent reason,” Locosselli said.

For Cerqueira, evidencing the lagging effects of rain and wind as causes of tree falls is one of the most significant aspects of the study. “Front-line municipal workers see what’s happening day to day, and know tree falls are reported all year long, but we used the dry season as a baseline,” she said. “The lagging effects of weather are important. Now we need to think about the action that should be taken immediately after stormy rain and wind to minimize the risk of tree falls, and to be ready to act if they happen.”

The researchers did not analyze the direct impact of age or pollution on tree health, but Locosselli said the fact that a large number of São Paulo’s trees were planted in the 1950s and 1960s contributes to their vulnerability and likelihood of falling.

With regard to air pollution, an article published in 2019 and co-authored by Locosselli showed that atmospheric pollutants stunt the growth of tipuana trees (Tipuana tipu), which are among the most common tree species in the city, and impair the ecosystem services they provide (more at: agencia.fapesp.br/30552).

Suggestions

Among the actions required to protect street trees in São Paulo, according to the study, are management and planning that takes into account species biology, resilience to extreme weather, and the characteristics of the local infrastructure.

The authors also recommend the implementation of tree monitoring programs using tree health indicators, and educational campaigns to win public support for science-based government decisions.

The City of São Paulo is legally responsible for managing street trees (Municipal Law 10,365/87). This includes planting, protecting tree health, pruning, and replacing trees when necessary. The actual work is outsourced to contractors. The electric power utility is allowed to trim tree crowns to make way for overhead power cables.

According to Cerqueira, a 20-year Municipal Urban Tree Plan was implemented in September 2020, aiming at planning and management to enhance resilience of the city to climate change, provision of shade and aesthetic benefits, and “satisfaction of the public”.

“Several aspects of tree management and planting highlighted in the study match the problems diagnosed by the Municipal Plan, which details programs and actions to address each problem,” she said.

The Plan is due for a review in 2025. For this first five-year period it sets priorities such as producing a fall risk analysis protocol and an emergency management project that includes an audit of the agreements signed with contractors and the utility in an effort to reduce the amount of pruning and damage to trees.

“The general public is more aware of the importance of trees. Popular participation has increased. When a tree falls, especially after a storm, we get many more calls. We plan to improve the technical material addressed to the public,” Cerqueira said.

With more than 12 million inhabitants, São Paulo has an area of 1,521 square kilometers and a subtropical climate. Roughly 75% of its streets have trees of various native species, including some from the Atlantic Rainforest, as well as exotic species, but most are in more central districts of the city. Planting more trees in outlying neighborhoods is one of the aims of the Municipal Plan.

Next steps

Locosselli said he has embarked on a new study with Cerqueira and other colleagues, analyzing georeferenced data available since 2012 for 30,000 trees in the city. “We’re looking at where trees are located to understand how tree falls are influenced by the surroundings and the environment. The study encompasses 19 variables, such as pollution, sidewalk width and slope, climate, and building height. We should be finished well before the end of the year,” he explained.

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About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at http://www.fapesp.br/en and visit FAPESP news agency at http://www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

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JOURNAL

Trees

DOI

10.1007/s00468-021-02145-4

METHOD OF RESEARCH

Case study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Climate drivers of tree fall on the streets of São Paulo, Brazil

ARTICLE PUBLICATION DATE

16-May-2021

HKUST scientists discover new mechanisms of activity improvement on bimetallic catalysts for hydrogen generation and fuel cells

Peer-Reviewed Publication

HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY

 

IMAGE: RUTHENIUM ATOMS SUPPORTED ON PLATINUM ARE EXTREMELY ACTIVE TO PRODUCE HYDROGEN view more 

CREDIT: HKUST

A group of researchers at the Hong Kong University of Science and Technology (HKUST) and Xiamen University has revealed new understandings of how surface ruthenium atoms can improve the hydrogen evolution and oxidation activities of platinum. This discovery opens a new venue for rational design of more advanced catalysts for electrolyzer and fuel cell applications. 

Hydrogen is a clean energy carrier that does not contain carbon. It is believed to play an essential role in our future sustainable society. Hydrogen can be produced from water via the hydrogen evolution reaction (HER) in an electrolyzer by using renewable energies, and consumed via a hydrogen oxidation reaction (HOR) in a fuel cell to generate electricity. Unfortunately, these two reactions are well-known kinetically sluggish in alkaline media, even on the most active platinum catalysts. The slow reaction rates limit the efficiencies of these two electrochemical devices and hinder their wide adoption. It has been known that the reaction rates of HER/HOR on platinum can be improved by surface modification or alloying with ruthenium. However, the mechanisms for this promotion have been under debate for over decades. Part of the reasons is a lack of direct observation of behaviors of hydrogen atoms on the surfaces of catalysts.

To reveal the enigma of high HER/HOR activities on platinum-ruthenium bimetallic catalysts, a research team led by Prof. Minhua Shao, Department of Chemical and Biological Engineering and Energy Institute at HKUST, recently applied the powerful surface-enhanced infrared absorption spectroscopy (SEIRAS) to directly monitor the binding strength of the important reaction intermediate, hydrogen atoms on various surfaces. Through the combined electrochemical, spectroscopic, and theoretical studies they confirmed the surface ruthenium atoms interacted with the sub-surface platinum is one order of magnitude more active than platinum, i.e., the ruthenium rather than platinum atoms are main active sites in this system. 

“Previous works mainly used conventional electrochemical and characterization techniques, which cannot directly monitor the adsorption behavior of hydrogen reaction intermediates. In this work, we use the powerful surface-enhanced infrared absorption spectroscopy, which is among the very few techniques that can directly “see” surface hydrogen atoms, and provides us more straightforward information on how ruthenium improves the activity” said Prof. Shao. “This work rules out the most widespread theory that the bifunctional effect on the interface between platinum and ruthenium is the cause of increased activities, and opens new directions on future design of more advanced HER/HOR catalysts, which can consequently reduce the usage of precious metals in both water electrolyzers and hydrogen fuel cells.”

This work is part of the newly founded Collaborative Research Fund project led by Prof. Shao “Development of high-performance and long-life alkaline membrane fuel cells”, and constitutes an important subsection of fundamental research to this whole project. Following works on the development of practical and high-performance bimetallic platinum-ruthenium electrocatalysts based on these findings is in progress.

This study was recently published in Nature Catalysis entitled “The Role of Ruthenium in Improving the Kinetics of Hydrogen Oxidation and Evolution Reactions of Platinum”.

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JOURNAL

Nature Catalysis

DOI

10.1038/s41929-021-00663-5

ARTICLE TITLE

The role of ruthenium in improving the kinetics of hydrogen oxidation and evolution reactions of platinum

ARTICLE PUBLICATION DATE

11-Aug-2021

UVA materials science engineers strive to reduce emissions from aircraft engines

Wadley Group innovates material and coating process to protect ceramic parts

Peer-Reviewed Publication

UNIVERSITY OF VIRGINIA SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Post-pandemic vacation travel was among the biggest stories of summer 2021, raising questions about air travel’s contribution to greenhouse gas emissions and climate change. According to the Environmental and Energy Study Institute, 710 million tons of global carbon dioxide came from commercial aviation in 2013. By 2017, that number reached 860 million tons, a 21% increase in four years. By 2018, it climbed to 905 million tons, 2.4% of total CO2 emissions.

Airplane manufacturers and their customers in government and industry have invested in the design of new aircraft engines that function at extremely high temperatures, which means the engines can generate more energy while burning less fuel. However, the very high temperatures can be a problem for the materials used to make the engine.

Haydn Wadley, Edgar Starke Professor of Materials Science and Engineering at the University of Virginia School of Engineering and Applied Science, and Jeroen Deijkers, a postdoctoral research associate in Wadley’s group, found a way to greatly extend the life of the materials used in these jet engines. Their paper, “A Duplex Bond Coat Approach to Environmental Barrier Coating Systems,” is published in the September 2021 issue of Acta Materialia.

“A jet engine gulps huge quantities of air, which, when compressed and mixed with hydrocarbon fuel and burned in a combustor, powers the plane’s propulsion system. The hotter the combustor, the more efficient the engine,” Wadley said.

Combustion in airplane engines now reaches or exceeds 1500 degrees centigrade, well above the melting temperatures of engine parts typically made of nickel and cobalt alloys. Research has turned to ceramics that can withstand these temperatures, but they must contend with chemical reactions from the water vapor and unburnt oxygen in the extreme combustion environment.

Silicon carbide is the ceramic of choice. However, engine parts made of silicon carbide would last only a few thousand hours of flight time. At such high temperatures, the carbon element reacts with oxygen to form carbon monoxide (a gas), while the silicon forms silica (a solid), but silica reacts with water vapor to form a gaseous silicon hydroxide. In other words, the engine part progressively turns into gas and disappears out the tail pipe.

To protect the ceramic parts, engine manufacturers apply a two-layer coating, called an environmental barrier coating system, to the silicon carbide. The outer layer is designed to slow the spread of oxygen and water vapor toward the silicon carbide during flight, while an inner bond coat made of silicon protects the silicon carbide’s surface by reacting with the oxygen to form a thin layer of silica. But there are still challenges to this design.

“The life of the engine component is often dictated by the time it takes for the silica layer thickness to reach a critical point where the stress caused by expansion and contraction during repeated heating and cooling causes the coating to pop off,” Wadley said.

Scientists and engineers have two basic strategies to delay the coating’s separation and extend the life of expensive engine components. They can make the outer coating layer very thick to slow down the arrival of oxygen at the bond coat, but that adds weight and cost. Or, they can create a different kind of protective oxide, one that does not “pop off.”

Deijkers and Wadley pursued the second strategy.

Their solution uses an outer layer of ytterbium disilicate, a rare earth element that shares silicon’s and silicon carbide’s thermal expansion characteristics and is slow to transport oxygen and water vapor toward the silicon layer. They first deposited the silicon bond coat and then placed a thin layer of hafnium oxide between the silicon and the ytterbium disilicate outer layer.

Their experimental studies show that as the silica forms on the silicon, it immediately reacts with the hafnia to form a silicon-hafnium oxide, or hafnon. The hafnon’s thermal expansion and contraction is the same as the rest of the coating and will never cause the coating to pop off or crack. Wadley calls it adding a little “hafnia fairy dust.”

“When we deposit a very thin layer of hafnia on top of silicon, followed by a layer of ytterbium disilicate, the oxygen that passes through the ytterbium disilicate creates a chemical reaction with the underlying materials to form the hafnon,” Deijkers said.

Deijkers’ access to unique equipment in Wadley’s lab, specifically a directed vapor deposition system, enabled this breakthrough in environmental barrier coatings. The ability to deposit a film of ytterbium disilicate that is thinner than the diameter of a human hair is key to their success.

The directed vapor deposition process uses a powerful 10-kilowatt focused electron beam to melt material in a low-pressure chamber. A supersonic gas jet transports the vapor to the silicon-coated silicon carbide where it condenses, creating a thin film. They then use a plasma spray method to deposit the final ytterbium disilicate layer, and the coated component is then ready for testing.

Deijkers successfully defended his dissertation in October 2020, combining his interests in aircraft and high-temperature materials for his Ph.D. research, and following his father’s path into materials science and engineering.

“My dad used to work on dredging ships. Seeing the pump house glowing orange-white in the furnace, that’s how I caught the engineering bug,” Deijkers said.

Deijkers, who is from the Netherlands, combined these early memories with his interest in serving in the Dutch Air Force, earning a bachelor’s and master’s degree in aerospace engineering from Delft University of Technology.

When Deijkers began applying to Ph.D. programs in the United States, his master’s thesis on thermal barrier coatings captured Wadley’s attention. Deijkers’ arrival was well timed. Group member Brad Richards, who earned his Ph.D. in materials science and engineering from UVA in 2015, had developed the silicon-ytterbium disilicate coating system for ceramics that was subsequently found to be very similar to that being used by the makers of aircraft engines.

Deijkers’ dissertation improves Richards’ coating system, deepening understanding of the surface chemistry involved and increasing the coating system’s viability for commercial adoption.

“One set of questions driving my research focused on how long it takes for the hafnon to form through the oxidation process,” Deijkers said. “I wanted to understand how this process really works, and whether we could actually put it to use.

“This coating has greater potential than we thought; we need to develop it and put it in an actual engine, to move it further along the path toward commercialization.”

Today’s methods are rooted in deposition techniques developed in the 1970s.

“Compared to the state-of-the-art in industry, our research makes a major improvement,” Deijkers said. “My rough estimate, if industrial manufacturers were able to implement these newer processing techniques, they could extend the engine parts’ lifetime by as much as 200 times. But there are a lot of hurdles to jump through to get that level of performance.”

Wadley’s research group made these advancements with the support of the Office of Naval Research, which awarded Wadley’s team two successive grants over a period of six years.

“The problems we have to solve are multi-disciplinary and multi-institutional,” Wadley said. “We need to fuse together knowledge from mechanics, chemistry and materials science in order to make progress. Beyond the immediate need to reduce CO2 emitted by propulsion technology, our research supports the global shift from carbon-containing hydrocarbons to hydrogen fuels and the eventual electrification of air travel platforms.”

Whereas Deijkers hopes to attract private industry to the team’s coatings system and deposition process, his career ambition is to pursue scientific discoveries at a national laboratory or in academia.

“The nation has an urgent need for talent in this arena,” Wadley said. “We are in desperate need for bright, creative people who want to be trained to solve these kinds of problems for society going forward.”

Just as Deijkers continued Richards’ research, he encourages UVA Engineering undergraduates to participate in the interdisciplinary research underway in Wadley’s group.

“We had undergraduates from aerospace engineering, physics, systems engineering,” Deijkers said. “We are working a lot of different aspects of the problem – computer modeling, materials synthesis, thermo-mechanical life design. We always have things for undergraduates to do, and we’re always open for them to do research with us.”

 

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JOURNAL

Acta Materialia

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A Duplex Bond Coat Approach to Environmental Barrier Coating Systems

ARTICLE PUBLICATION DATE

15-Sep-2021

 

Study takes unprecedented peek into life

 of 17,000-year-old mammoth

Peer-Reviewed Publication

UNIVERSITY OF ALASKA FAIRBANKS

 

IMAGE: A CLOSE-UP VIEW SHOWS A SPLIT MAMMOTH TUSK AT THE ALASKA STABLE ISOTOPE FACILITY. BLUE STAIN IS USED TO REVEAL GROWTH LINES. SAMPLES WERE TAKEN ALONG THE TUSK USING LASERS AND OTHER TECHNIQUES, ALLOWING ISOTOPE ANALYSIS THAT PROVIDED A RECORD OF THE MAMMOTH’S LIFE. view more 

CREDIT: PHOTO BY JR ANCHETA, UNIVERSITY OF ALASKA FAIRBANKS

An international research team has retraced the astonishing lifetime journey of an Arctic woolly mammoth, which covered enough of the Alaska landscape during its 28 years to almost circle the Earth twice.

Scientists gathered unprecedented details of its life through analysis of a 17,000-year-old fossil from the University of Alaska Museum of the North. By generating and studying isotopic data in the mammoth’s tusk, they were able to match its movements and diet with isotopic maps of the region.

Few details have been known about the lives and movements of woolly mammoths, and the study offers the first evidence that they traveled vast distances. An outline of the mammoth’s life is detailed in the new issue of the journal Science.

“It’s not clear-cut if it was a seasonal migrator, but it covered some serious ground,” said University of Alaska Fairbanks researcher Matthew Wooller, senior and co-lead author of the paper. “It visited many parts of Alaska at some point during its lifetime, which is pretty amazing when you think about how big that area is.”

Researchers at the Alaska Stable Isotope Facility, where Wooller is director, split the 6-foot tusk lengthwise and generated about 400,000 microscopic data points using a laser and other techniques.

The detailed isotope analyses they made are possible because of the way that mammoth tusks grew. Mammoths steadily added new layers on a daily basis throughout their lives. When the tusk was split lengthwise for sampling, these growth bands looked like stacked ice cream cones, offering a chronological record of an entire mammoth’s life.

“From the moment they’re born until the day they die, they’ve got a diary and it’s written in their tusks,” said Pat Druckenmiller, a paleontologist and director of the UA Museum of the North. “Mother Nature doesn’t usually offer up such convenient and life-long records of an individual’s life.”

Scientists knew that the mammoth died on Alaska’s North Slope above the Arctic Circle, where its remains were excavated by a team that included UAF’s Dan Mann and Pam Groves, who are among the co-authors of the study.

Researchers pieced together the mammoth’s journey up to that point by analyzing isotopic signatures in its tusk from the elements strontium and oxygen, which were matched with maps predicting isotope variations across Alaska. Researchers created the maps by analyzing the teeth of hundreds of small rodents from across Alaska held in the museum’s collections. The animals travel relatively small distances during their lifetimes and represent local isotope signals.

Using that local dataset, they mapped isotope variation across Alaska, providing a baseline to trace the mammoth movements. After taking geographic barriers into account and the average distance it traveled each week, researchers used a novel spatial modeling approach to chart the likely routes the animal took during its life.

Ancient DNA preserved in the mammoth’s remains allowed the team to identify it as a male that was related to the last group of its species that lived in mainland Alaska. Those details provided more insight into the animal’s life and behavior, said Beth Shapiro, who led the DNA component of the study.

For example, an abrupt shift in its isotopic signature, ecology and movement at about age 15 probably coincided with the mammoth being kicked out of its herd, mirroring a pattern seen in some modern-day male elephants.

“Knowing that he was male provided a better biological context in which we could interpret the isotopic data,” said Shapiro, a professor at the University of California Santa Cruz and investigator at the Howard Hughes Medical Institute.

Isotopes also offered a clue about what led to the animal’s demise. Nitrogen isotopes spiked during the final winter of its life, a signal that can be a hallmark of starvation in mammals.

“It’s just amazing what we were able to see and do with this data,” said co-lead author Clement Bataille, a researcher from the University of Ottawa who led the modeling effort in collaboration with Amy Willis at the University of Washington.

Discovering more about the lives of extinct species satisfies more than curiosity, said Wooller, a professor in the UAF College of Fisheries and Ocean and Institute of Northern Engineering. Those details could be surprisingly relevant today as many species adapt their movement patterns and ranges with the shifting climate.

“The Arctic is seeing a lot of changes now, and we can use the past to see how the future may play out for species today and in the future,” Wooller said. “Trying to solve this detective story is an example of how our planet and ecosystems react in the face of environmental change.”

Other institutions contributing to the study included Florida State University, Montanuniversität Leoben, Liaocheng University and the National Park Service.

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JOURNAL

Science

DOI

10.1126/science.abg1134

ARTICLE TITLE

Lifetime Mobility of an Arctic Woolly Mammoth

ARTICLE PUBLICATION DATE

13-Aug-2021

Isotopes reveal the lifetime mobility of an Arctic woolly mammoth

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

From the isotopes inside a 1.7-meter-long tusk, researchers recreated the life history of one Arctic woolly mammoth that lived more than 17,000 years ago, offering some of the first evidence that woolly mammoths traveled vast distances. Their findings provide a window into the lives of these now-extinct creatures, including their preferred habitats and extensive lifetime range. Despite being one of the most widely studied and iconic ice-age creatures, very little is known about the natural life history of the woolly mammoth, as fossils alone provide only static and often singular glimpses into their lives. Thus, the home range and mobility of mammoths – where and how far the large creatures roamed throughout their lives – remains largely a mystery. However, since regular migrations across great distances characterize the mobility patterns of their living elephant relatives and other Arctic animals, it is assumed that woolly mammoths exhibited similar behaviors. One method of potentially reconstructing the mobility patterns of long-dead mammoths is through the analysis of oxygen and strontium (Sr) isotopes that become incorporated into the animals’ teeth and tusks during life. Strontium isotope ratios (87Sr/86Sr) in soils and plants reflect the underlying bedrock geology, which vary across landscapes. As animals eat these plants, 87Sr/86Sr patterns from the region become incorporated into tissues. Thus, the 87Sr/86Sr ratios contained in tissues that continually grow throughout life, like mammoth tusks, for example, can provide a record that can be used to trace an animal’s movement over time. Using the tusk from a male woolly mammoth that lived in what is now mainland Alaska more than 17,100 years ago, Matthew Wooller and colleagues assembled a high temporal resolution isotopic record that reveals – in great detail – the mammoth’s movements during its ~28-year lifespan. The record shows repeatedly traveled routes across a geographically extensive range, with the animal covering enough of the Alaska landscape during its 28 years to almost circle the Earth twice. The results also illustrate the regions the animal frequented during different life stages, including as an infant and juvenile when part of a herd, as a more broadly traveling prime-aged adult, and during its final years, where, in a small region in northern Alaska, it likely succumbed to starvation.

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JOURNAL

Science

DOI

10.1126/science.abg1134

ARTICLE TITLE

Lifetime Mobility of an Arctic Woolly Mammoth

ARTICLE PUBLICATION DATE

13-Aug-2021

Study investigates how arctic-alpine plants respond to global warming

500 million measurements on the impact of climate change

Peer-Reviewed Publication

UNIVERSITY OF BONN

 

IMAGE: THE DWARF BIRCH (SHOWN HERE WITH REDDISH LEAVES) COULD BENEFIT FROM CLIMATE CHANGE. view more 

CREDIT: © ROLAND PAPE / UNIVERSITY OF SOUTH-EASTERN NORWAY

It is the most comprehensive study of its kind to date: Researchers at the University of Bonn and the University of South-Eastern Norway have studied how two characteristic arctic-alpine plant species respond to global warming. They did this by analyzing almost 500 million of their own readings from the mountainous region of Norway. The analyses show that potential consequences of climate change are extremely dependent on the specific location of the plants and that deciduous species in particular will benefit from warming. The result would be a further increase in the trend toward greening of the arctic-alpine regions. The study is published in the journal Ecosphere.

The Norwegian mountains can be pretty darn inhospitable during the colder months. Nevertheless, there are plants that cope splendidly with the biting temperatures. They include the dwarf birch Betula nana and the black crowberry Empetrum hermaphroditum. Both thrive in arctic-alpine conditions; this makes them typical representatives of tundra vegetation.

Up until now, it has been unclear how the growth of dwarf birch and crowberry is influenced by specific environmental conditions. In the alpine regions of Norway, a project has been underway for 30 years that aims to change that. "We wired up some of the plants here and fitted them with so-called data loggers that record the measurements," explains Prof. Dr. Jörg Löffler from the Department of Geography at the University of Bonn. A pin-like sensor records the diameter of the trunk - minute by minute, 365 days a year, to an accuracy of less than a thousandth of a millimeter. At the same time, the researchers measure solar radiation, temperature in the root zone and just above the soil surface, and soil moisture.

Shrinkage against frost damage

In the current study, researchers analyzed nearly 500 million measurements from 40 plants between 2015 and 2019. "We mainly studied how the microclimate, that is, the conditions encountered by the individual plant, affects its growth," says Svenja Dobbert, who is doing her doctorate in Prof. Löffler's research group. This revealed a striking rhythm in both dwarf birch and crowberry: During the colder months, their trunk diameter shrank significantly in each case - a process that was reversed in the spring. However, it was not until late summer that the deficits were made up to such an extent that actual growth began.

CAPTION

The dwarf birch (shown here) loses its foliage in winter, but the crowberry is evergreen.

CREDIT

© Roland Pape / University of South-Eastern Norway

"Due to low temperatures in the colder months, there is hardly any liquid water available for the plants," Dobbert says, explaining the finding. "They also reduce their trunk diameter by even actively reducing the water content of their cells to avoid frost damage." Just how important this strategy is for both species to thrive is demonstrated by another observation: Plants that shrank very little during the winter often showed little or no growth the following summer.

A second important finding: The deciduous dwarf birches usually grew better after a mild winter. They therefore seem to generally benefit from warmer winters. With the evergreen crowberries it was the other way around. "In cold winters, there is usually less snowfall," Löffler says. "This could be an advantage for evergreen species because they can then keep up photosynthetic activity for longer and hence enter the growth phase earlier in the spring." It is therefore possible that climate change is causing an increasing spread of deciduous species and a concomitant displacement of evergreen species. Since the leaves of deciduous plants have a comparatively large surface area (in contrast, those of evergreen species are usually needle-like), this effect could contribute to the further greening of arctic-alpine regions.

The microclimate is crucial

"However, our results also show that microclimatic conditions can be extremely different depending on the location," explains Löffler. For instance, at exposed, windy locations, snow cover tends to be very thin. The deciduous dwarf birch however requires a sufficiently thick insulating layer of snow in winter. It then has to use fewer resources to protect itself from frost. Without this warming blanket, the dwarf birch has a difficult time. The evergreen crowberry, in contrast, benefits from the extra sunlight during such snow-free periods. "Overall, our measurements prove that global climate data provide little valid evidence for local vegetation effects," emphasizes the geographer. "Studies like ours can potentially help us better model such complex effects and in turn better predict the effects of climate change on plant life."

Participating institutions:
In addition to the University of Bonn, the University of South-Eastern Norway was involved in the study.

Publication: Svenja Dobbert, Roland Pape & Jörg Löffler: Contrasting growth response of evergreen and deciduous arctic-alpine shrub species to climate variability. Ecosphere, https://doi.org/10.1002/ecs2.3688

CAPTION

The crowberry (shown here) is evergreen, but the dwarf birch loses its foliage in winter.

CREDIT

© Roland Pape / University of South-Eastern Norway

JOURNAL

Ecosphere

DOI

10.1002/ecs2.3688