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How weather and climate shape Earth's life-sustaining surface

Anonymous — Thu, 06 Dec 2018 15:00:00 +0000

How weather and climate shape Earth's life-sustaining surface Anonymous (not verified) Thu, 12/06/2018 - 08:00

Trent Knoss

We know less about the ground beneath our feet than we do about the surface of Mars, but new research by University of Colorado Boulder geoscientists shines a light on this hidden world from ridgetops to valley floors and shows how rainfall shapes the part of our planet that is just beyond where we can see.

Earth is popularly known as the “third rock from the sun,” yet hard rock is rare at the ground surface. Scientists have dubbed the vegetation, soil and water-storing debris that hides Earth’s rocky interior from view the “critical zone.” The name honors the fact that this zone is simultaneously essential to life and is shaped by living organisms. The character of the critical zone – particularly its depth – controls how groundwater is stored and released to streams.

Groundwater provides the water supplies that are the lifeblood of agriculture and industry in the nation, and indeed around the world. But groundwater itself is not passive. It reacts with the rock along its path, and in so doing both chemically transforms the rock and picks up dissolved minerals and nutrients.

The researchers were inspired to study the fundamental differences between two National Science Foundation-supported Critical Zone Observatories (CZOs). In the Boulder Creek CZO in the Colorado Front Range, fresh rock can be found beneath a thin layer of soil and broken rock that evenly mantles hillsides. In the Calhoun CZO in the South Carolina piedmont, fresh rock is far below the surface, and the critical zone billows thickly under ridge crests and thins under valley bottoms. And the soils of Colorado are gray-brown and rocky, in contrast to the red clays of South Carolina.

The CU Boulder researchers set out to understand why this life-sustaining and water-storing blanket of soil and the underlying weathered rock vary so much from one place to another. Co-authors included Distinguished Professor Robert S. Anderson of CU Boulder’s Department of Geological Sciences, President’s Teaching Scholar Professor Harihar Rajaram of CU Boulder’s Department of Civil, Environmental, and Architectural Engineering, and Professor Suzanne P. Anderson of CU Boulder’s Department of Geography.

“Our goal was to create a model to explain why these differences occur,” said Suzanne Anderson.

The researchers focused on one of the most obvious differences between the two sites: the weather. They built a numerical model to test whether the much greater rainfall in the southeast could explain the great differences in the depth of weathering. In the model, rainwater is tracked as it seeps through the landscape, and causes rock minerals to weather (or transform) into clay. Because weathering processes are slow, it was necessary to include soil formation and erosion as well.

“Weathering of bedrock may be the most important geologic process, since it produces the soil we depend on for our existence,” says Richard Yuretich, director of the NSF Critical Zone Observatories program, which funded the research.

The results, published today in a special issue of the journal Hydrological Processes devoted to the role of water in the critical zone, show that a shallow Colorado-type critical zone forms under dry conditions, while a thick, undulating South Carolina-type critical zone forms in wet conditions.

In other words, the model succeeds in explaining the drastic differences in these landscapes. The connectivity of the system captivated the research team.

“It’s fascinating how simple patterns in critical zone thickness respond to climate, to erosion, and undoubtedly to processes that we haven’t considered yet,” said Suzanne Anderson, who is also a fellow of CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR).“Being able to predict these patterns of weathering puts us in a position to understand things we care about, from water supplies to maintaining healthy soils.”

“Soil resources are precious,” said Robert Anderson, also an INSTAAR fellow. “One of the aspects of the landscape that we had to embrace in this modeling effort is that it takes thousands of years to generate the soil we have. If it is scraped away or misused, it’s not going to be replaced in human timescales. Mismanagement means you will never get it back.”

“But to me”, he said, “it is interesting enough, and satisfying enough, to explain why you can dig a pit 20 feet deep with a shovel in South Carolina, and have to resort to a pick axe within two feet in Colorado. It’s all about the weather.”

New research shines a light on how rainfall shapes ridgetops, valley floors and the critical zone of Earth's surface.

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When it rains, snake bites soar

Anonymous — Wed, 05 Sep 2018 17:19:57 +0000

When it rains, snake bites soar Anonymous (not verified) Wed, 09/05/2018 - 11:19

Daniel Strain

Hikers and trail runners be warned: Rattlesnakes and other venomous reptiles may bite more people during rainy years than in seasons wracked by drought, a new study shows.

The research, which was led by Caleb Phillips of CU Boulder and Grant Lipman of the Stanford University School of Medicine, examined 20 years of snake bite data from across California. Their findings contradict a popular theory among many wilderness health professionals that drought might increase snake bites by pushing the reptiles out into the open where they are more likely to run into people.

Instead, the group discovered that for every 10 percent increase in rainfall over the previous 18 months, cases of snake bites spiked by 3.9 percent in California’s 58 counties. In other words, while rattlesnakes may not sing in the rain, they seem to bite more when the climate gets wet.

The results could have implications for efforts to prevent and treat dangerous encounters between humans and snakes—especially as climate patterns shift across the western United States.

“This study shows a possible unexpected, secondary result of climate change,” said Phillips, an adjunct assistant professor in CU Boulder’s Department of Computer Science. “We probably need to take climatological changes into account when we coordinate systems that may seem unrelated like planning how we distribute antivenin supplies or funding poison control centers.”

Trail sightings

The team suspects that the reason for the surge in snake bites during wet years may come down to snake food. Mice and other rodents, the prime meals for rattlesnakes, flourish in rainy years—and that might give snakes a boost.

Colorado is home to a scaly trio of venomous pit vipers. From top to bottom, the prairie rattlesnake (Crotalus viridis), massasauga rattlesnake (Sistrurus catenatus) and western rattlesnake (Crotalus oreganus). (Credits: CC photo by Todd Pierson via Flickr; CC photo by Tim Vicekrs via Wikimedia Commons; CC photo by California Department of Fish and Wildlife via Flickr)

Phillips and Lipman decided to probe this hazard because of a mutual hobby: trail running. “I’m an outdoor nerd,” Phillips said. “I run a lot on South Table Mesa in Golden, and I see a number of rattlesnakes out there.”

The researchers wondered how climate change might influence the frequency of such encounters. They pored through 5,365 cases of rattlesnake bites reported to the California Poison Control System between 1997 and 2017. The team compared those cases to a range of other information, including climate data from NASA and drought records from the National Drought Mitigation Center.

What the group found was surprising: When California counties experienced drought, recorded cases of snake bites dropped off. Those incidences hit record low levels statewide in 2015 and 2016 when California was in the middle of a historic dry spell. The decrease isn’t huge, but “it’s a significant change if you’re considering the public health implications,” Phillips said.

The researchers published their findings today in the journal Clinical Toxicology.

Outdoor safety

The broader implications of the study are still up in the air. Research in Colorado and other parts of the United States suggests that the impact of warming temperatures on rainfall patterns will be a mixed bag, with some regions experiencing more severe storms and others seeing drier weather.

Phillips said that he’d be eager to find out if the same trends appear outside of California. Colorado is home to three closely-related species of venomous reptiles: prairie, western and massasauga rattlesnakes. Bites from these animals rarely kill humans, but tragedy can strike. Colorado triathlete Dan Hohs, for example, died from a rattlesnake bite in 2017.

Regardless, Phillips urges outdoor enthusiasts like himself to stay calm. He is a trained wilderness first responder and emergency medical technician and said that you can avoid snakes with a simple strategy: give rattlers plenty of room and exercise common sense.

“If you encounter a rattlesnake,” Phillips said, “don’t pick a fight with it, and it won’t pick a fight with you.”

For more information about avoiding and responding to snake bites, see this tip sheet from the U.S. Centers for Disease Control and Prevention.

Other co-authors of the study include Derrick Lung and Hallam Gugelman of the University of California, San Francisco School of Medicine and Katie Doering of the Stanford School of Medicine.

Hikers and trail runners be warned: Rattlesnakes and other venomous reptiles may bite more people during rainy years than in seasons wracked by drought, a new study shows.

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Pushing Boundaries: Grad students think like barn swallows to craft an artistic nesting site

Anonymous — Wed, 05 Sep 2018 16:18:29 +0000

Pushing Boundaries: Grad students think like barn swallows to craft an artistic nesting site Anonymous (not verified) Wed, 09/05/2018 - 10:18

Kenna Bruner

For hundreds of years, barn swallows have signaled the coming of spring. In many cultures, it is considered good luck to have barn swallows build nests on a person’s property.

Artifacts depicting barn swallows can be found throughout the world: in hieroglyphs at the pyramids in Egypt, on Bronze Age pottery, in cave paintings in France and Greece, and on Native American Lakota art.

Listen to the podcast

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Distinguished by their deeply forked tails, dark blue bodies and reddish breasts, barn swallows can be seen swooping low over the water and land in search of flying insects to feed their young. Barn swallows once built their mud nests in caves and on rock cliffs throughout North America, but they now construct nests almost exclusively on built structures, such as barns, sheds, underpasses and abandoned buildings.

Humans and barn swallows have long coexisted peacefully, but several factors have dramatically reduced the birds’ numbers, one of which is a lack of available structures for the birds to use. Learning more about their breeding and migration habits, and providing more places they can use to nest, could help researchers determine how to protect them.

Rebecca Safran, associate professor of ecology and evolutionary biology at CU Boulder, and her group of student researchers have teamed up with Aaron Treher, lecturer in the Department of Art and Art History who developed a novel approach to conservation that’s part site-specific artwork and part structure to entice the birds into making it their home. If successful, the structure could be a model for similar ones in urban areas.

“The conservation status of barn swallows is declining precipitously,” Safran said. “Our goal with this installation was to create a structure that not only highlights the science and conservation concerns, but also the interesting co-existence we have with barn swallows and shows that they really do live side-by-side with us.”

Barn swallows can be found in Colorado from mid-April until the end of September and lay multiple broods during that time. They build a cup nest from mud pellets and feeds on insects caught in flight. The barn swallow’s song is a cheerful warble. One of the benefits of our coexistence with them is that a barn swallow consumes more than 800 mosquitoes a day.

Molly McDermott, a PhD student, and Treher, an MFA graduate, collaborated on the wooden sculpture that has been installed at a barn swallow colony on private land north of Boulder.

The site-specific artwork is attached to the barn on land owned by Richard Cargill. Safran and her team have been researching barn swallows at Cargill’s barn for more than 10 years. One of the tagged birds has been returning to the barn for seven years. It’s one of several study sites in Boulder County used by Safran and her team this summer. They have studied barn swallows throughout most of their breeding distribution in Asia, Europe,the Middle East, North Africa and North America.

The creation of the artwork began as Treher’s thesis work for his master’s degree. He named the structure the Observation Station. Its distinctive shape—a horizontal box stacked askew on top of a vertical box—is his interpretation of what a structure might look like if barn swallows designed it and how they might stack the two segments.

“We’re trying to find out how we can create more nesting space for barn swallows,” Treher said. “I designed it to appeal to the needs of the barn swallows and to make it so the landowner is comfortable with how it looks. All these different places around the world have building traditions that work with the ecology of a place. Finding the overlap between art and ecology is the sweet spot of my work.”

McDermott, who studies ecology and evolutionary biology, focuses her research on migration and how that interacts with barn swallow breeding biology.

She has been trying to lure swallows in by removing old nests from the original colony inside the barn and attaching them inside the sculpture. She has displayed a stuffed swallow to pique their interest and plays recordings of barn swallow songs. It all appears to be working, because 10 individual birds have made hundredsof visits to the sculpture this summer.

“We want to know what conditions will get these birds to visit this sculpture that’s designed as a way to augment their habitat,” McDermott said. “How can we induce birds to use spaces like this so we can learn what access they like? Signals from other swallows are important to them. Thinking another swallow has visited or is using the sculpture will attract them.”

The Observation Station, which represents an integration of art, science and community, is sponsored in part by Nature, Environment, Science & Technology (NEST) Studio for the Arts. NEST is a CU Boulder initiative that encourages artists and scientists to work together on a project. It was also sponsored by a scholarship from the sculpture and post-studio practice (SPS) area in the Department of Art and Art History, and the Art and Rural Environments Field School SPS area that promotes artwork that is collaborative, interdisciplinary, and environmentally and culturally aware.

Additional funds to sponsor the upcoming showcase of this project are provided by Inside the Greenhouse, an art/science collaborative initiative also at CU Boulder, founded by Safran and Associate Professors Beth Osnes (theatre and dance) and Max Boykoff (ENVS/CIRES/CSTPR).

“We want to show that you can actually move a population of swallows into a structure like this to give them more places to build nests,” Safran said.

Community art and science event

If you go

Who: Open to the public
What: Community art and science event
When: Saturday, Sept. 15
Presentations: 1–2:30 p.m.
Open house: 2:30–5 p.m.
Where: Cargill Ranch and Silk Road Studio, 11768 North 59th St.

Side By Side is a community art and science event scheduled for 1 to 5 p.m. Sept. 15 at Cargill Ranch and Silk Road Studio, 11768 North 59th St., Hygiene, Colorado.

The event is being held on the property of one of the landowners Safran’s team works with. Activities will include a walk-through of the site and exploration of the installation and its relationship to the barn swallows they study.

Artists and scientists collaborating for conservation research on barn swallows in Colorado and worldwide will give presentations from 1 to 2:30 p.m. The open house will take place from 2:30 to 5 p.m. It will include a tour of the Observation Station, a site-specific artwork and sound installation; viewing barn swallow nesting sites; refreshments and kids’ activities.

Side By Side is sponsored by NEST Studio for the Arts, Inside the Greenhouse, the sculpture and post-studio practice area in the Department of Art and Art History, and the Art and Rural Environments Field School.

The event grew from an interdisciplinary collaboration between artists and biologists at CU Boulder, who are interested in celebrating shared space with wildlife, focusing on barn swallows—a declining songbird species that nests exclusively in human-made spaces.

Side by Side is a community art and science event focused on barn swallows, a declining songbird species that nests exclusively in human-made spaces.

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Alpine ecosystems struggle to recover from air pollution

Anonymous — Tue, 04 Sep 2018 11:00:00 +0000

Alpine ecosystems struggle to recover from air pollution Anonymous (not verified) Tue, 09/04/2018 - 05:00

Trent Knoss

What happens to high mountain ecosystems when you take away air pollution? Not much, not very quickly.

A new CU research study finds that degraded alpine ecosystems showed limited recovery years after long-term inputs of human-caused nitrogen air pollution, with soil acidification and effects on biodiversity lingering even after a decade of much lower nitrogen input levels.

The study, which was recently published in the journal Ecological Applications, indicates that even a dramatic reduction in nitrogen emissions may not be sufficient to reverse changes to various ecosystem processes after decades of high exposure.

“The legacy of the impacts of nitrogen pollution is strong, and our results emphasize that sensitive standards are needed to minimize enduring environmental impacts,” said William Bowman, lead author of the study and a professor in CU Boulder’s Department of Ecology and Evolutionary Biology (EBIO).

Nitrogen is a key nutrient for life, but agricultural and industrial activities have increased global levels significantly over the last two centuries, with previous research indicating harmful effects on water quality, soil acidity and biodiversity. Nitrogen emission rates have slowed in most of the U.S. and Europe in recent years, but continue to increase in developing regions.

The new study explores the extent to which alpine ecosystems can recover or reverse the effects of nitrogen deposition even after input levels have slowed. To test the difference, CU Boulder researchers used a long-running set of field plots first established in 1997 on Colorado’s Niwot Ridge at an elevation of 11,400 feet. The plots had been artificially exposed to varying levels of additional nitrogen over the course of 12 years.

Beginning in 2009, the researchers divided the plots in half, continuing to fertilize one half at the same rate while cutting off nitrogen to the other. Then, they followed the changes in the plots’ biotic composition and ecosystem processes for nine more years, tracking changes in plant diversity, microbial abundance and soil acidity.

Overall, the researchers found that vegetation recovery was more limited in the areas that had received the highest levels of nitrogen previously, even after gaining a reprieve in subsequent years. Bacteria and fungi abundances also remained lowered and soil remained acidic, indicating sustained impacts that cannot be easily reversed.

“The altered chemistry and biology of the ecosystem stimulated the rates of nitrogen cycling in the soil, extending the negative impacts of a high nitrogen condition,” Bowman said. Additionally, some recovery processes operate at geologic scales, relying on the breakdown of the rocks and soil particles that can take decades or longer.

The findings indicate that many of the effects of human-caused nitrogen deposition may already be baked into ecosystems and hamper their recovery regardless of future decreases in emission rates, a crucial consideration for setting environmental regulations and pollution standards.

Additional co-authors of the research include Cliff Bueno de Mesquita, Noah Fierer, Stefanie Sternagel and Teal Potter of CU Boulder and Asma Ayyad of University of California Riverside. The National Science Foundation provided funding for the study via the Niwot Ridge Long-Term Ecological Research Project and a Research Experiences for Undergraduates Grant.

Degraded alpine ecosystems showed limited recovery years after long-term inputs of human-caused nitrogen air pollution.

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Rain-on-snow flood risk to increase in many U.S. mountain regions

Anonymous — Mon, 06 Aug 2018 15:00:00 +0000

Rain-on-snow flood risk to increase in many U.S. mountain regions Anonymous (not verified) Mon, 08/06/2018 - 09:00

Trent Knoss

Flooding caused by rain falling on snowpack could more than double by the end of this century in some areas of the western U.S. and Canada due to climate change, according to new research from CU Boulder and the National Center for Atmospheric Research (NCAR).

The greatest flood risk increases are projected for the Sierra Nevada, the Colorado River headwaters and the Canadian Rocky Mountains—places where residents are no strangers to flood concerns. Conversely, lower elevations in coastal regions of California, Oregon, Washington and maritime British Columbia could see decreases in rain-on-snow flood risk.

The findings were published today in the journal Nature Climate Change.

Rain-on-snow events vary widely in timing and scale but can cause costly and damaging flooding as rapid snowmelt triggered by heavy and prolonged rainfall converge in a cascade that can overwhelm downstream rivers and reservoirs. In 2017, California’s Oroville Dam nearly failed catastrophically due to such an event, leading to the evacuation of 188,000 people and $1 billion in infrastructure damages.

“Rain-on-snow events can be intense and dangerous in mountainous areas, but they are still relatively poorly understood,” said Keith Musselman, lead author of the study and a research associate at CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR). “We can infer a little bit from streamflow, but we want to get better measurements and model more of the variables involved.”

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To study the past, present and potential future of rain-on-snow events, the researchers turned to a state-of-the-art weather modeling dataset developed at NCAR. Known as CONUS 1, the dataset contains weather simulations across the continental U.S. in the current climate and a warmer future based on projected climate trends. The enormous data trove—which took NCAR’s Yellowstone supercomputer more than a year to compile—offers unprecedented detail and resolution.

“This high-res dataset allows us to resolve mountains in granular fashion and examine the factors that combine to melt the snowpack when a warm storm comes in and hits cold mountains like the Sierra,” Musselman said.

The authors found that in a warmer climate, less frequent snow-cover at lower elevations would decrease the risk for rain-on-snow flood events in areas like the U.S. Pacific Northwest. By contrast, at higher elevations where winter snow will still accumulate despite climate warming (such as in the High Sierra and much of the Rocky Mountains), rain-on-snow events could become more frequent due to increased rainfall that might once have fallen as snow. The events will also become more intense.

The rain and melt produced during rain-on-snow events is projected to increase for a majority of western North American river basins as rain rather than snow affects more mountain watersheds, increasing the corresponding flood risk by as much as 200 percent in localized areas and potentially straining existing flood control infrastructure.

“We were surprised at how big some of the projected changes were,” Musselman said. “We didn’t expect to see huge percentage increases in places that already have rain-on-snow flooding.”

The findings represent an important first step toward better understanding rain-on-snow flood risk in the context of anthropogenic climate change, which could significantly shift the timing and extent of future flood regimes.

The researchers hope that continued investment in snowpack monitoring networks and efforts such as NASA’s Airborne Snow Observatory will provide additional ground information, allowing hydrologists and climate scientists to verify their models against observations and better inform flood risk assessment now and in the future.

The study was co-authored by NCAR researchers Flavio Lehner, Kyoko Ikeda, Martyn Clark, Andreas Prein, Changhai Liu, Mike Barlage and Roy Rasmussen. NCAR is sponsored by the National Science Foundation.

Flooding caused by rain falling on snowpack could more than double by the end of this century in some areas of the western U.S. and Canada due to climate change.

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Billion-year-old lake deposit yields clues to Earth's ancient life

Anonymous — Wed, 18 Jul 2018 06:00:00 +0000

Billion-year-old lake deposit yields clues to Earth's ancient life Anonymous (not verified) Wed, 07/18/2018 - 00:00

A sample of ancient oxygen, teased out of a 1.4-billion-year-old evaporative lake deposit in Ontario, Canada, provides fresh evidence of what the Earth’s atmosphere and biosphere were like during the interval leading up to the emergence of animal life.

“It’s mind-boggling to think about, but this really is ‘fossil’ atmospheric oxygen captured in minerals much in the same way that ancient atmospheric gasses get trapped as bubbles in ice cores,” said Boswell Wing, senior co-author of the new research and an associate professor in the Department of Geological Sciences at CU Boulder.

The findings, published in the journal Nature, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years.

“It has been suggested for many decades now that the oxygen content of the atmosphere has significantly varied through time,” said Peter Crockford, who led the study as a Ph.D. student at McGill University. “We provide unambiguous evidence that it was indeed much different 1.4 billion years ago and identify a mechanism—a much less productive biosphere—that may help explain why.”

A smaller biosphere

The study provides the oldest gauge yet of what earth scientists refer to as “primary production,” in which micro-organisms at the base of the food chain—algae, cyanobacteria and the like—produce organic matter from carbon dioxide and pour oxygen into the air.

“We can see from these measurements that primary production 1.4 billion years ago was a tiny fraction of today’s,” said Wing, formerly of McGill University. “This tells us that the biosphere, the sum total of all life on earth, had to be smaller as well. There just may not have been enough food—organic carbon—to support a lot of complex macroscopic life.”

To come up with these findings, Crockford teamed up with colleagues from Yale University, University of California Riverside and Lakehead University in Thunder Bay, Ontario, who had collected pristine samples of ancient sulfate salts like gypsum, found in a sedimentary rock formation north of Lake Superior. Crockford shuttled the samples to Louisiana State University where he worked closely with co-authors Huiming Bao, Justin Hayles and Yongbo Peng, whose lab is one of handful in the world using a specialized mass-spectrometry technique capable of probing such materials for rare oxygen isotopes within sulfate salts.

The work also sheds new light on a stretch of Earth’s history known as the “boring billion” because it yielded little evidence for biological or environmental change.

“Subdued primary productivity during the mid-Proterozoic era—roughly 2 billion to 800 million years ago—has long been implied, but no hard data had been generated to lend strong support to this idea,” noted Galen Halverson, a co-author of the study and associate professor of earth and planetary sciences at McGill. “That left open the possibility that there was another explanation for why the middle Proterozoic ocean was so uninteresting, in terms of the production and deposit of organic carbon.”

The new data “provide the direct evidence that this boring carbon cycle was due to low primary productivity.”

Throughout Earth's history, oxygen levels in the atmosphere have risen in lock-step with the emergence of complex life. (Credit: Peter Crockford)

Exoplanet clues

The findings could also help inform astronomers’ search for life outside our own solar system.

“For most of Earth history our planet was populated with microbes, and projecting into the future they will likely be the stewards of the planet long after we are gone,” said Crockford, now a postdoctoral researcher at Princeton University and Israel’s Weizmann Institute of Science. “Understanding the environments they shape not only informs us of our own past and how we got here, but also provides clues to what we might find if we discover an inhabited exoplanet.”

This story was modified from a version by McGill University.

Researchers say that scant supplies of oxygen may have existed in Earth's ancient atmosphere.

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The sunflower's rapid evolutionary transformation

Anonymous — Mon, 11 Jun 2018 19:00:00 +0000

The sunflower's rapid evolutionary transformation Anonymous (not verified) Mon, 06/11/2018 - 13:00

Trent Knoss

A new CU Boulder-led study sheds light on the genetic mechanisms that allowed sunflowers to undergo a relatively rapid evolutionary transition from wild to domesticated in just over 5,000 years.

Sunflowers, prized for their seeds and oil, have long held agricultural value for humans. Wild, ancestral varieties of the common sunflower Helianthus annuusare widely distributed across North America and grow smaller seeds than their domesticated counterparts, which have been selected over time for prominent single flower heads and larger seeds with high quality oil.

The new study focused on untangling the biological phenomenon of alternative splicing, a regulatory mechanism that allows multicellular organisms to code multiple RNA transcripts and proteins from a single gene. Alternative splicing creates useful efficiencies, but also introduces variation over time. The origins and contributions of alternative splicing to major evolutionary transitions—especially over short periods of time—remain largely unknown.

Researchers used RNA sequencing to compare a domesticated H. annuusvariety with a wild variety of the same species, focusing on 226 clear cases of splicing differentiation. They were able to identify the genetic regulation of splicing for 134 distinct genes, and found patterns suggesting that this mechanism underlies important domestication traits that have manifested under strong human-induced breeding.

“We were surprised to find that splicing differences were attributable to relatively few regulatory changes” said Chris Smith, a graduate researcher in CU Boulder’s Department of Ecology and Evolutionary Biology (EBIO) and the lead author of the study. “We expect that further down the road, various other species could be analyzed this way, too.”

The findings, which could have broader implications for agricultural production and scientists’ understanding of genetic divergence, were published today in the journal Proceedings of the National Academy of Sciences.

Co-authors of the new study include CU Boulder Assistant Professor Nolan Kane, Silas Tittes, Paul Mendieta and Erin Collier-zans of EBIO along with Heather Rowe and Loren Rieseberg of the University of British Columbia Vancouver. Genome Canada and Genome BC’s Applied Genomics Research in Bioproducts or Crops Competition provided funding for the research.

A new study sheds light on the genetic mechanisms that allowed sunflowers to undergo a relatively rapid evolutionary transition from wild to domesticated in just over 5,000 years.

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