Among the Academies: Questions for Plants

As the planet warms, how will plants respond? For a clue, evolutionary ecologists like Sharon Strauss can move a plant outside of its comfort zone.

Strauss, a distinguished professor emerita of evolution and ecology, has conducted numerous experiments growing plants under conditions where they aren’t usually found, with the aim of studying how they’ll respond.

“One of the things that I love about working with plants is that they can’t move. So you can force them to grow in areas or under conditions where they don't grow by just planting them there,” Strauss said. “And if they germinate or survive there, then you can say, ‘How do you like living there? And what are the reasons that you don't thrive there?’”

Strauss said her goal is to learn about the ecological niche of a given species — the place where it thrives. For example, the rainfall must be adequate, the soil must contain the right nutrients and the plants can’t all become food for animals.

Strauss’ work has earned her numerous accolades, including election to the National Academy of Sciences, the American Academy of Arts and Sciences, the California Academy of Sciences and more. 

Open to surprises

In a series of related projects, Strauss and other researchers planted dozens of related plants over the course of several years at UC Davis’ Bodega Marine Reserve. They were testing a theory from Charles Darwin that said more closely related species would compete more fiercely for resources, and found it true, although a 2016 study included a surprise finding that habitat suitability decreased as the plants became less-closely related, then increased again with distant relatives.

Strauss and others theorized soil biology might have explained those later results. She has also examined soil as it relates to the way native jewelflowers — members of the mustard family — are able to thrive in harsh serpentine soils, which have high concentrations of nickel and low availability of calcium. Strauss wondered which aspects of soil composition were most important in promoting adaptation to use these soils. She “ran around California” collecting soil samples from multiple sites of almost all species of jewelflowers, and put soil elemental composition as a trait on the evolutionary tree of jewelflowers, along with other ecological traits like how many neighbors a plant had within a small radius. She could then map which of these properties were most associated with the evolutionary shift to serpentine soils. But again, what she found was a surprise: The jewelflowers that had adapted to serpentine soils had not come from ancestors that grew in soils with either high nickel or low calcium, as she had hypothesized. The ability to grow on serpentine soil came from adaptations to coarser soils that held less water, and thus also supported fewer other plants — they were more barren environments with coarse soils that were chemically unrelated to serpentine. Few studies had considered “bareness” as an important ecological selective force, but since this study, others have found adaptation to the stresses of bare environments to be important, Strauss said. 

“I think where you make big jumps is when your paradigm is not supported,” Strauss said. “It’s the fun part of science that you always think you might know what’s going on, but then in reality, you find that nature is full of processes and things that you haven’t thought about in your limited human brain that end up opening a lot of new doors.”

She said when asking questions, a starting point is a must — but so is flexibility.

“You have to be open to the organism telling you that framework isn't right,” she said.

An urban upbringing

While Strauss has had successes advancing our understanding of nature, she grew up in the country’s biggest city.

“People always say, ‘How did someone who grew up a New York City become an ecologist?’” she said, recalling her family satisfying “nature cravings” with trips to the mountains, along with frequent visits to the Central Park Zoo and the American Museum of Natural History. She said she grew up hoping to study animals until a friend in college opened her eyes to plants.

“I just loved doing experiments,” she said. “And if you’re going to do experiments, there’s nothing that beats a plant. You can’t take an animal and make it grow in the niche of another animal. But because plants can’t run away, you can just force them to do all sorts of things that they wouldn't normally do, and then they can tell you, ‘Oh, my leaves are turning yellow — I’m not getting the right nutrients.’”

Strauss did her undergraduate studies at Harvard University, where she was mentored by Maureen Stanton, a doctoral student who would go on to teach at UC Davis. Strauss then earned a master’s degree at the University of Minnesota and a doctorate at Florida State University. After graduation, she did a postdoctorate in entomology at UC Davis and then moved to the University of Illinois Urbana-Champaign. She returned to UC Davis in 1994 when she and her husband, conservation scientist Mark Schwartz, both found jobs with the university.

Helping students find their niche

Another major focus of Strauss’ career has been mentorship. She founded the UC Davis chapter of the Ecological Society of America’s SEEDS program, or Strategies for Ecology Education, Diversity and Sustainability, which provides support for students underrepresented in ecology. It was named the society’s chapter of the year in 2014.

She said her lab followed an “old fashioned” model that allowed students wide leeway to choose their own projects and fields of study — something that was only possible because UC Davis’ collaborative environment made it easy for Strauss to refer a grad student to another faculty member for help in an area outside her expertise.

“And I learned a lot in the process because then I’ve learned about these other areas and eventually, that feeds back into your own thinking of the world,” she said, noting that conducting research with and training graduate students has been “my favorite part of this job.”

The expertise of researchers at UC Davis opened doors to all kinds of projects; Strauss recalled one grad student who was looking to extract a specific type of chemical from leaves, and was able to work with the Department of Viticulture and Enology to do so.

“As a plant person, Davis is incredible, between all of the horticultural, agricultural and ecological resources,” Strauss said. “There’s just so many resources here — especially if you work on plants — it’s mind blowing.”

Her enthusiasm for research hasn’t waned — despite transitioning to emerita status in 2021, she continues to publish research. She is staying engaged and continues to think about the future of her field; she is looking ahead to the impact that AI could have on finding new information from massive data sets collected over many years.

“This has been a great career — super fun and interesting — and I've loved it. So why would I want to stop?”