Biology

Western aster gives hope for managing cheatgrass

Anonymous — Tue, 14 Nov 2023 17:00:58 +0000

Western aster gives hope for managing cheatgrass Anonymous (not verified) Tue, 11/14/2023 - 10:00

Jeff Mitton

In Rabbit Valley near the Colorado-Utah border, some signs indicate that aster could stymie the dominance of the invasive species

Cheatgrass, Bromus tectorum, is an invading species that now dominates millions of acres in North America. Although it is found in all 50 states, it has been particularly troublesome in rangeland in the western states and in sagebrush environments of the Great Basin.

Its original native distribution included the Mediterranean region of Europe, northern Africa and southwestern Asia. It was first reported in New York and Pennsylvania in 1861 and made its way to the western states by the 1880s. Cheatgrass is probably the most successful invader in North America—in the Great Basin alone it is estimated to cover 81,000 square miles.

Between the 1830s and 1880s, biologists were not monitoring the appearance and movement of invading species as they are today. But given that cheatgrass seemed to spread with agriculture and with ranching, it seems likely that its seeds were one of the impurities of seed lots bought by farmers and ranchers. But in addition, it is known that cheatgrass was also purposely planted in search of a grass that would support more livestock.

Western aster and cheatgrass grow in Rabbit Valley near the Colorado-Utah border.

The most distressing facet of cheatgrass is how it invades communities, displaces established species and dominates grasslands and sagebrush communities. It certainly followed cows, for early management of cows generally led to overgrazed landscapes, which were quickly colonized by cheatgrass. But cheatgrass has a variety of advantages that make it a successful weed, and once established, a dominant that is difficult to eradicate.

Cheatgrass is a winter annual. It sets seeds in late summer and in contrast to many annual grass species, its seeds germinate in the fall. By spring, it has a large root system, and its shoots develop and are photosynthesizing long before its competitors. The early, rhizomatous root system is able to absorb and store much water, leaving parched soil for native grasses. Cheatgrass grows quickly in spring, reaching heights of 3 to 4 feet, creating abundant seeds and more bulk than native grasses.

The plants dry as their seeds mature, dramatically changing the appearance of the landscape—spring's lush and abundant greenery loses its nutritional value as green turns gold and the seeds develop long awns—spikes from the maturing seeds that can injure cattle. Perhaps the common name "cheat" comes from the sudden transformation from excellent food for cattle in spring to very little of available nutritive value in mid-summer.

Finally, once cheatgrass becomes established, its greater accumulation of dry grass is fuel that changes the fire regime of the local environment. Instead of fires returning in 50 to 150 years, fires recur more frequently, providing this winter annual with another advantage over native grasses.

When I first started camping in the McInnis Canyons National Conservation Area west of Grand Junction, I was beguiled by the mesas and canyons but horrified by the condition of Rabbit Valley, which appeared to be a monoculture of cheatgrass. However, during my most recent trip to Rabbit Valley, I saw something that suggested either evolutionary or ecological conditions were changing.

Western aster grows amid a near-monoculture of cheatgrass in western Colorado's Rabbit Valley.

Western aster, Symphyotrichum ascendens, was growing among the cheatgrass in the Knowles Overlook campground. I had not seen them before, or perhaps I did not notice them before. But the asters were in flower and they grew taller than the cheatgrass, so they were conspicuous. I looked around with binoculars and was delighted to find that western asters were mixed with cheatgrass throughout Rabbit Valley. In a few places, asters were abundant.

Western aster is a perennial, rhizomatous forb native to all states west of the Great Plains. Under good conditions, it can grow to be 4 feet tall, bearing numerous flowers. It is known as the most common, widespread and variable aster species. It is extremely variable because it arose from hybridization of S. spathulatum and S. falcatum, and it now hybridizes with both species.

Furthermore, its geographic range is large, and it is adapted to a wide elevational range and both mesic and arid environments. Species with large geographic ranges and adaptations to numerous habitats generally have high levels of genetic variation. which is needed for rapid evolutionary and ecological responses to novel challenges.

Apparently, I am not the first to have noticed western asters moving into areas dominated by cheatgrass. A literature survey turned up a U.S. Department of Agriculture plant guide, which stated that western aster could compete with and even suppress cheatgrass.

I am hoping that Rabbit Valley is a theater featuring increasing competitive ability of a widespread native species to the most successful invading species in the West.

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In Rabbit Valley near the Colorado-Utah border, some signs indicate that aster could stymie the dominance of the invasive species.

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Small but not simple, bacteria compute without thinking

Anonymous — Fri, 01 Sep 2023 21:26:41 +0000

Small but not simple, bacteria compute without thinking Anonymous (not verified) Fri, 09/01/2023 - 15:26

Rachel Sauer

New ��ý�Ļ��Ʒ research shows that bacteria harness physical laws to operate at the edge of chaos and use calcium to independently diversify and find a place to settle down

Let’s talk about the bacteria in our colons.

Like all life on this planet, their main goal is to replicate their genome, passing it on to the next generation. But hostile environments like the colon force them to make tough choices: Hunker down here or swim farther downstream in hopes of greener pastures?

Meanwhile, all their kin are making the same calculation. Each has the same genome but can’t follow the same instruction manual or else they’ll all land on the same spot. They must diversify. So, how does a single-cell organism lacking the benefit of billions of neurons know how to do that?

Newly published research finds that bacteria—and not just the kinds in our colons, but many types in many environments—use changes in calcium, controlled through a process called “self-organized criticality,” to spontaneously diversify without the need for communication between cells. Bacteria use calcium not only in governing the transition to a biofilm, but in movement, maintaining cell structure and in infection.

Christian Meyer, a postdoctoral fellow in the University of Colorado Boulder Department of Molecular, Cellular and Developmental Biology, researched how bacteria use calcium to diversify.

Understanding how calcium is regulated in bacteria may have significant future implications for, among other applications, treating harmful biofilms that can form on surfaces. Further research may help scientists interrupt a bacterium’s calcium dynamics, perhaps preventing it from settling on a surface in the first place.

“Bacteria have so much to teach us,” says Christian Meyer, a postdoctoral fellow in the University of Colorado Boulder Department of Molecular, Cellular and Developmental Biology who completed the research with former ��ý�Ļ��Ʒ assistant professor Joel Kralj. “There’s a fallacy in assuming that because something is small, it’s simple. Bacteria are using statistical mechanics to run computations instantaneously that I run over an entire weekend on my computer.”

Not more evolved than bacteria

In fact, Meyer’s research was inspired, in part, by the prevalent notion that humans are the pinnacle of evolution and the idea that “we’re more evolved than ________”—than amoebas, than earthworms, than bacteria.

“That’s not at all what evolutionary theory is saying,” Meyer notes. “The theory is that you, as a human, would make a horrible worm. Each unto their own niche. There are lots of systems in the natural world that operate without ‘intelligence,’ by which I mean that bacteria aren’t sitting there with a billion neurons at their disposal to figure out how much calcium they should let in right now. They have to do that rapidly and in changing environments, but also energy efficiently, and do it instantaneously—they’re not thinking.”

Originally, Meyer and his research colleagues studied antibiotics and how they modify the electrophysiology—or the electrical properties of cells that include current and voltage—of bacteria. They showed that E. coli bacteria, when treated with certain antibiotics, respond with changes in membrane potential.

In hundreds of videos of antibiotic-treated bacteria, the scientists watched calcium, as a marker of cell membrane voltage, going in and out of the cell. Instead of general randomness in that process, they saw power laws at work. Power laws describe the probability of an event happening as a function of its magnitude or duration. For example, the relationship between the probability and magnitude of an earthquake follows a power law, with large earthquakes being less likely than small ones.

Through further research with strains of E. coli, B. subtilis and P. putida bacteria, they found that calcium fluctuations resulted from a property known as self-organized criticality (SOC). SOC is a general property of many natural systems that are poised at the boundary between two phases without external control. Rather than separate states of matter, the phases are defined as different dynamical regimes, and often SOC systems are poised at the boundary between ordered and chaotic dynamics—what has been described as “order at the edge of chaos.”

Using self-organized criticality

Meyer and Kralj found that SOC can explain how bacteria cells exist on a knife’s edge between very high levels of calcium outside the cell and calcium levels that are about 100,000 times lower inside the cell. At high levels, calcium can be cytotoxic, meaning it can damage or kill cells. So, the bacteria‘s membranes operates somewhat like a dam, opening and closing rapidly and often—but not in a consistent pattern—to pump calcium in and out.

Bacteria expressing a fluorescent calcium sensor.

The research findings also suggest an evolutionary advantage of SOC, because it provides a way for individual bacteria to diversify, even without communicating with one another. SOC could be compared to a random number generator inside each bacteria cell, one that’s power law-based “so big events are more likely than they would be otherwise,” Meyer says.

“Because of this, going back to the example of bacteria in the colon, a bacterium will swim farther down the colon than it would if it was just randomly swimming. This is an extremely efficiently search strategy, to use power law-based searches in a domain. From my perspective, I think how incredible it is that they’re using a physical process to run computations to figure out what they should be doing, all without talking to each other or ‘thinking’.”

While understanding how calcium dynamics in bacteria result from SOC is an important step, further research will need to study how to target calcium while leaving a bacterium’s membrane electrical voltage intact. Then researchers can begin working toward applications like treating harmful biofilms.

“I’ve really grown to admire what bacteria are capable of doing,” Meyer says. “Imagine being a one-femtoliter cell (one-quadrillionth of a liter) and having to survive in the crazy world we live in with all the changes in temperature and pH and nutrients. It’s a hard world, but they’ve come up with incredibly elegant solutions to the complex challenges they face.

“In some ways, I’ve been inspired thinking how can we co-opt some of these natural processes for solving some of the issues humans face and do it in an intelligent way, things bacteria figured out a long time ago. SOC systems are an interesting mixture of flexible yet robust without the need for constant tuning. These seem desirable properties for many anthropogenic systems, from AI to social networks. I’ve come to appreciate bacteria as good examples of combating that fallacy of we are the pinnacle of evolution. They have amazing secrets to teach us, we just have to look at them.”

Top image: AI-generated picture of bacteria

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New ��ý�Ļ��Ʒ research shows that bacteria harness physical laws to operate at the edge of chaos and use calcium to independently diversify and find a place to settle down.

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‘Classroom in the sky’ inspires generations of researchers, students

Anonymous — Fri, 02 Jun 2023 20:34:46 +0000

‘Classroom in the sky’ inspires generations of researchers, students Anonymous (not verified) Fri, 06/02/2023 - 14:34

Cay Leytham-Powell

As the Mountain Research Station celebrates turning 100, a look back on its history—and toward its future

The sky was a perfect crystal blue as 50 undergraduate students from the University of Colorado Boulder spent their Saturday atop a mountain clustered around grasshoppers.

Plastic cages scarcely taller than the swaying golden grasses lay scattered about—some excluding the insects, others preventing their escape—all to see how the creatures responded to the vegetation within.

Rather than assist with the research, which was being conducted by a postdoctoral student from the University of Oregon, these general biology students hiked up a narrow, rugged path amid dense pine and yellowing aspens to this break in the trees, called Elk Meadow, to learn about research—both its legacy and its future almost 10,000 feet above sea level.

Top of the page: Bill Bowman works with a student up on the tundra. Photo by Patrick Campbell/University of Colorado Boulder. Above: The Mountain Research Station is run by a dedicated set of staff, students and faculty who maintain equipment, gather data and work on one of the most beautiful parts of ��ý�Ļ��Ʒ's campus. (Credit: ��ý�Ļ��Ʒ)

Just north of Nederland, about 26 miles from Boulder, is ��ý�Ļ��Ʒ’s “classroom in the sky”—the Mountain Research Station. It is the university’s highest research facility and is home to some of the world’s longest-running alpine research, from how trees respond to increasing wildfires, to the charismatic little pikas and chickadees that call these slopes home, to the changing composition of the soil itself.

Graduate students and some undergraduates in the natural sciences find their way here. And yet general biology students have rarely had the opportunity to visit and learn about the facility—until now.

“You usually see graduate students or faculty or staff up there, but undergrads are rarer,” explains Warren Sconiers, an associate teaching professor in the Department of Ecology and Evolutionary Biology (EBIO) at ��ý�Ļ��Ʒ and the trip’s organizer.

“We (EBIO professors) want them to know what opportunities there are in research, and as soon as they realize it, and as soon as they want to (participate), get them out here as a part of the research at Boulder.”

The Mountain Research Station’s legacy

The Mountain Research Station has long been a pilar of support for alpine research and education. And that legacy is clear in the make-up of the place itself—from classrooms and offices to a dining hall and living spaces to bird-nest boxes used to study hybridization hanging on pine trees.

The Mountain Research Station, originally known as Science Lodge and Science Camp, was built in 1920 on what once was federal land. It is one of the oldest alpine field research facilities in the world, and one of the best, argues Bill Bowman, the station’s former director and a professor emeritus in EBIO. Bowman says that is in large part because of the staff that make this this place run and the expert leadership of John Marr, who became the station’s director in 1950.

Marr founded many of the programs the station is now known for, like the Mountain Climate Program, and provided the scientific groundwork for the current Niwot Ridge Long-Term Ecological Research (LTER) program, which is funded by the National Science Foundation and researches how mountain ecosystems are transforming in response to climate change. It is the only LTER spot focusing on alpine environments in North America and is one of the original LTERs, continuously funded since 1980.

Additionally, through the Mountain Climate Program—created to evaluate the relationship between climate and the major ecosystem types of the Front Range—the station is home to the longest continuous record of greenhouse gas measurements in the continental United States, found above timberline at around 11,500 feet, and the second-longest in the world, behind only the station on Mauna Loa in Hawaii.

The long-term data that’s been collected here is really priceless, and I think being at a place that’s contributed so much to our understanding of long-term change in climate and ecosystems is really special.”

“It’s really been one of the main places on the planet where we’ve learned about long-term changes in climate and mountain ecosystems,” says Scott Taylor, the station’s director and an associate professor in EBIO. “The long-term data that’s been collected here is really priceless, and I think being at a place that’s contributed so much to our understanding of long-term change in climate and ecosystems is really special.”

In addition to the LTER program and Mountain Climate Program, the Boulder Creek Critical Zone Program and the National Ecological Observatory Network (NEON) also conduct research near the station.

“We wouldn’t be able to do half of what we’ve done at the Mountain Research Station if it weren’t for (Marr’s) efforts,” Bowman says.

Taylor agrees, adding that the Mountain Research Station is “really unique. . . . Lots of places have research stations, but not a lot have this kind of history.”

That history, though, extends past just data to the people who have found their way here through the decades.

Generations of care

Bowman became involved with the station in the 1970s as an undergraduate in environmental, population and organismic biology (now EBIO and integrative physiology). At the time, Bowman worked with a graduate student in the lab of Professor Emeritus Jeff Mitton, who was studying forest genetics and needed help getting pine needle samples to run genetic analyses on them. Bowman, who loved to hike and snowshoe, volunteered.

Fast-forwarding through multiple graduate degrees, Bowman found himself back in Boulder, but this time as a professor. He was invited to participate in the LTER program, which at that time was more concerned with physical-environment conditions than with biology. Through his participation, Bowman began researching plant ecology and what factors determined which plants occurred where, how communities came together to alter the diversity, and how that influences ecosystem functioning.

It was through Bowman’s lab that Katharine Suding, now the principal investigator for the LTER program and a Distinguished Professor in EBIO, became involved in the program, then as a postdoctoral researcher.

In 1990, a few years after Bowman began his alpine research, he became the station’s director and stayed there for 30 years, until his retirement in 2021.

During his tenure, many repairs were completed on the station, including upgrading infrastructure and building the Moores-Collins Family Lodge and Kiowa classroom, which is across the parking lot from the Marr Lab, where the main offices are housed. He also helped start or expand several large research programs, which provided data for something that Bowman saw firsthand for decades: the effects of climate change on the station.

“I’ve clearly seen climate change come and establish itself as being something that we recognize and we can see symptoms of,” Bowman says. “Climate change is a factor that’s going to become more and more important in how the station operates.”

Additionally, under Bowman’s leadership, the Research Experiences for Undergraduates (REU) program, funded by the National Science Foundation, was established at the station. For more than 20 years, that program has brought undergraduates, including Sconiers, from across the United States and the globe to Colorado during the summers.

“It’s gratifying for the faculty who set those (REU) programs up to be able to see the investment come to fruition and see it passed on,” Bowman says. “That’s one of the most satisfying things that I’ve gotten while being director of the Mountain Research Station.”

Inspiring those to come

Sconiers was a student at the University of California, Irvine when he learned about the station. At the time, he was interested in research and graduate school but knew he needed to join a lab to do that. He began contacting faculty around campus, and one of them, Suding, then at UC Irvine, said yes—and recommended he pursue an REU.

Scott Taylor's research applies genomics and field experiments to natural hybrid zones and closely related taxa in order to investigate the architecture of reproductive isolation—the hallmark of speciation—and the genetic bases of traits relevant to speciation.

He applied and was accepted by the program at the Mountain Research Station. While there, he helped collect data detailing how the alpine landscape had been altered in response to climate change.

“The REU was critical for my career,” Sconiers says. “It was my first opportunity to devise a project from scratch, so come up with my own ideas and have it fit into a research interest, and then I got to collect all of the data, so I got to carry it through. In class, you’re just learning how this works or doing small versions of things, but this was the first chance I had to do everything.”

After graduating, Sconiers was a lab tech for Suding for a year before going on to graduate school for entomology. He eventually became a professor at the University of the Ozarks in Arkansas and stayed there for a few years.

It was about that time that he ran into Suding, who told him about an opening at ��ý�Ļ��Ʒ.

That brought him back to the university, this time as a teaching professor and a researcher with the Institute of Arctic and Alpine Research—which runs the Mountain Research Station—where he studies how plant species composition affects insect diversity at high elevations.

By bringing his general biology students to the station, he hopes to introduce the next generation of scholars to its possibilities.

“The idea of the trip was so the students can talk with the faculty who do research there and potentially just be up there for research and other things, so really just to take this resource that’s unique to ��ý�Ļ��Ʒ and introduce it to students,” Sconiers says. “Let them know that you can have an interest, and that’s enough to get involved.”

Taylor, who hopes to use his tenure as director to make the station more visible and inclusive for everyone, is thrilled.

“There’s the scientific legacy of the station, but then also there’s one of inspiring generations to care about alpine ecosystems and mountain ecosystems,” Taylor says.

“That’s partially why I love field stations. They have such a big impact—a disproportional impact.”

As the Mountain Research Station celebrates turning 100, a look back on its history—and toward its future.

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Physicists win prestigious Sloan Fellowships

Anonymous — Wed, 22 Feb 2023 21:18:43 +0000

Physicists win prestigious Sloan Fellowships Anonymous (not verified) Wed, 02/22/2023 - 14:18

Orit Peleg and Shuo Sun are among 125 early-career scholars who represent ‘the most promising scientific researchers working today’

Two University of Colorado Boulder physicists have been named Sloan Research Fellows, the organization announced last week.

Orit Peleg, assistant professor of physics and computer science, and Shuo Sun, assistant professor of physics, are among 125 early-career scholars who represent “the most promising scientific researchers working today,” the Sloan Foundation said.

Winners receive $75,000, which may be spent over a two-year term on any expense supporting their research.

Sloan Research Fellows are shining examples of innovative and impactful research ... We are thrilled to support their groundbreaking work, and we look forward to following their continued success."

"Sloan Research Fellows are shining examples of innovative and impactful research,” said Adam F. Falk, president of the Alfred P. Sloan Foundation. “We are thrilled to support their groundbreaking work, and we look forward to following their continued success."

A Sloan Research Fellowship is a particularly notable recognition for young researchers, in part because so many past fellows have gone on to become “towering figures in science,” the foundation said.

Peleg’s research strives to understanding how biological communication signals are generated and interpreted, and it does so by merging tools from physics, biology, engineering and computer science. Her research has yielded insight into the behavior of bees and fireflies, which are seen at the top of the page.

Orit Peleg seeks to understand the behavior of disordered living systems by merging tools from physics, biology, engineering, and computer science.

Peleg said she was grateful that her research, which she is “deeply passionate about,” resonates with others in the field. “I owe a great debt of gratitude to my supportive colleagues, mentors, and mentees who have guided me throughout my journey,” she said.

“With the awarded funding, I aim to gain a more comprehensive understanding of the spatiotemporal dynamics of collective communication signals in nature across an increasing array of model species. This area is enormously rich, full of exciting and confounding questions, with a range as expansive as the diversity of life.”

Peleg joined the ��ý�Ļ��Ʒ faculty in 2018. She earned a PhD in materials science in 2012 from ETH Zürich, Switzerland, and holds master’s and bachelor’s degrees in physics and computer science from Bar–Ilan University, Israel.

Sun’s research explores light-matter interactions at the fundamental quantum limit, where single atoms can strongly interact with single photons. This is done by designing and fabricating nanophotonic structures that confine photons at an extremely small volume, which are then coupled to solid-state artificial atoms such as quantum dots and atomic defect centers.

Sun joined the ��ý�Ļ��Ʒ faculty in 2019 as a visiting assistant professor of physics and has been an assistant professor of physics since 2020. He is also an associate fellow in JILA, a physical science research institute at ��ý�Ļ��Ʒ. He holds a PhD and MS in electrical engineering from the University of Maryland, College Park, and a BS in optics from Zhejiang University in Hangzhou, China.

This year’s fellows come from 54 institutions across the United States and Canada.

Shuo Sun is an assistant professor of Physics and an associate fellow of JILA.

Renowned physicists Richard Feynman and Murray Gell-Mann were Sloan Research Fellows, as was mathematician John Nash, one of the fathers of modern game theory. Some 56 fellows have received a Nobel Prize in their respective field, 17 have won the Fields Medal in mathematics, and 22 have won the John Bates Clark Medal in economics, including every winner since 2007.

Open to scholars in seven scientific and technical fields—chemistry, computer science, Earth system science, economics, mathematics, neuroscience and physics—Sloan Research Fellowships are awarded in close coordination with the scientific community. Candidates must be nominated by their fellow scientists. Winners are selected by independent panels of senior scholars on the basis of candidates’ research accomplishments, creativity and potential to become a leader in their field.

Peleg and Sun bring the total number of Sloan Fellows recognized at ��ý�Ļ��Ʒ to 65 since 1961. They raise the number of ��ý�Ļ��Ʒ Sloan Fellows in physics to 24.

More than 1,000 researchers are nominated each year for 125 fellowship slots. A full list of the 2023 Fellows cohort is available at https://sloan.org/fellowships/2023-Fellows.

Orit Peleg and Shuo Sun are among 125 early-career scholars who represent ‘the most promising scientific researchers working today.’

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Biology

Western aster gives hope for managing cheatgrass

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