Bonnie Jacobs

Research: SMU scientists help solve the mystery of climate and leaf size

Conifer needlesWhy is a banana leaf a million times bigger than a common heather leaf? Why are leaves generally much larger in tropical jungles than in temperate forests and deserts? The textbooks say it’s a balance between water availability and overheating – but researchers have found that it’s not that simple.

SMU paleobotanist Bonnie F. Jacobs has contributed work to a major new study that provides scientists with a new tool for understanding both ancient and future climate by looking at the size of plant leaves.

The study, published in the Sept. 1, 2017 issue of Science, was led by Associate Professor Ian Wright from Macquarie University, Australia. The study’s findings reveal that in much of the world the key factor limiting the size of a plant’s leaves is the temperature at night and the risk of frost damage to leaves.

Jacobs said the implications of the study are significant for enabling scientists to either predict modern leaf size in the distant future, or to understand the climate for a locality as it may have been in the past.

“This research provides scientists with another tool for predicting future changes in vegetation, given climate change, and for describing ancient climate given fossil leaves,” said Jacobs, a professor in SMU’s Roy M. Huffington Department of Earth Sciences in the Dedman College of Humanities and Sciences.

“Now we can reliably use this as another way to look at future climate models for a specific location and predict the size of plant leaves,” she said. “Or, if we’re trying to understand what the climate was for a prehistoric site tens of millions of years ago, we can look at the plant fossils discovered in that location and describe what the climate most likely was at that time.”

Wright, Jacobs and 15 colleagues from Australia, the U.K., Canada, Argentina, the United States, Estonia, Spain and China analyzed leaves from more than 7,600 species, then pooled and analyzed the data with new theory to create a series of equations that can predict the maximum viable leaf size anywhere in the world based on the risk of daytime overheating and night-time freezing.

The researchers will use these findings to create more accurate vegetation models. This will be used by governments to predict how vegetation will change locally and globally under climate change, and to plan for adaptation.

“The conventional explanation was that water availability and overheating were the two major limits to leaf size. But the data didn’t fit,” says Wright. “For example the tropics are both wet and hot, and leaves in cooler parts of the world are unlikely to overheat.”

“Our team worked both ends of the problem – observation and theory,” he says. “We used big data – measurements made on tens of thousands of leaves. By sampling across all continents, climate zones and plant types we were able to show that simple ‘rules’ seemingly operate across the world’s plant species, rules that were not apparent from previous, more limited analyses.”

Jacobs contributed an extensive leaf database she compiled about 20 years ago, funded by a National Science Foundation grant. She analyzed the leaf characteristics of 880 species of modern tropical African plants, which occurred in various combinations among 30 plant communities. Jacobs measured leaves of the plant specimens at the Missouri Botanical Garden Herbarium, one of the largest archives of pressed dried plant specimens from around the world.

She looked at all aspects of leaf shape and climate, ranging from seasonal and annual rainfall and temperature for each locale, as well as leaf shape, size, tip, base, among others. Using statistical analyses to plot the variables, she found the most prominent relationship between leaf shape and climate was that size increases with rainfall amount. Wet sites had species with larger leaves than dry sites.

Her Africa database was added to those of many other scientists who have compiled similar data for other localities around the world.

— Written by Margaret Allen

> Read the full story from the SMU Research blog

Four professors honored with 2013 Ford Research Fellowships

SMU 2013 Ford Research Fellows Thomas Ritz, Bonnie Jacobs, Michael Corris and Suku Nair

Four SMU professors were honored with 2013 Ford Research Fellowships during the University’s May Board of Trustees meeting (left to right): Thomas Ritz, Bonnie Jacobs, Michael Corris and Suku Nair.

Four exemplary SMU researchers have been chosen as the University’s 2013 Ford Research Fellows. This year’s recipients are Michael Corris, Art, Meadows School of the Arts; Bonnie Jacobs, Earth Sciences, Dedman College of Humanities and Sciences; Suku Nair, Computer Science and Engineering, Lyle School of Engineering; and Thomas Ritz, Psychology, Dedman College of Humanities and Sciences.

Established in 2002 through a $1 million pledge from SMU Trustee Gerald J. Ford, the fellowships help the University retain and reward outstanding scholars. Each recipient receives a cash prize for research support during the year.

Learn more about the new Fellows under the link.

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SMU fossils, expertise to be an ongoing part of new Perot Museum

Malawisaurus in the Perot Museum

A 35-foot skeletal cast of the Early Cretaceous sauropod dinosaur Malawisaurus stands sentry in the spacious glass lobby of the new Perot Museum of Nature and Science in Dallas. SMU paleontologist Louis Jacobs, who discovered the dinosaur in Africa, provided the cast to the museum. (Image: Dallas Morning News)

SMU faculty and students, the University’s Shuler Museum of Paleontology, and the SMU Innovation Gymnasium have teamed with the nation’s new premier museum of nature and science to provide everything from dinosaurs and sea turtles to technical assistance and advice.

Fossils on loan by SMU to Dallas’s new Perot Museum of Nature and Science include those of animals from an ancient sea that once covered Dallas.

The fossils represent a slice of SMU’s scientific collaboration with the Perot Museum and its predecessor, the Dallas Museum of Natural History.

Items from SMU’s scientists include a 35-foot skeletal cast of the African dinosaur Malawisaurus (pictured above) standing sentry in the spacious glass lobby of the Perot, which opened Dec. 1 near downtown Dallas.

“The new museum building itself is an icon, but it’s also a statement by the city about taking the advances of science to the public,” said vertebrate paleontologist Louis Jacobs, an SMU earth sciences professor, who serves on the Perot Museum’s advisory board and Collections Committee.

Jacobs, who was ad interim director of the Dallas Museum of Natural History in 1999, led the team that discovered Malawisaurus in Africa. He provided the cast to the museum.

“Here at SMU we train students and create new knowledge. The museum’s mission is to take the stories of science out to the general public so they can be used,” said Jacobs. “Anthony Fiorillo, Perot Museum Curator of Earth Sciences, is a world-class scientist with whom we work. We have a junction between the mission, training and knowledge we have here, infused into and enhanced by what the museum does. That’s why the museum is important to SMU and that’s why SMU is important to the museum.”

Fossils on loan are from the Shuler Museum collection in the Roy M. Huffington Department of Earth Sciences. SMU scientists provided technical expertise for exhibits and serve on the Perot Museum’s advisory committees.

Also on exhibit from SMU is a miniature unmanned autonomous helicopter designed for fighting fires that was built by students in SMU’s Lyle School of Engineering.

Shuler Museum fossils can be viewed in the T. Boone Pickens Life Then and Now Hall. They include an unnamed 113 million-year-old herbivorous dinosaur discovered in 1985 at Proctor Lake southwest of Stephenville, Texas.

For perspective on that exhibit’s paleoenvironment in Texas at the time, SMU paleobotanist Bonnie Jacobs provided fossil wood, fossil cones, fossil leaves and images of microscopic pollen grains from the Shuler Museum. The fossils provided information used to create a model of an extinct tree to accompany the exhibit.

> Read the full story from the SMU Research blog

Research Spotlight: New fossils challenge old preconceptions

Bonnie JacobsFor paleobotanist Bonnie Jacobs standing atop a mountain in the highlands of northwest Ethiopia, it’s as if she can see forever – or at least as far back as 30 million years ago.

Jacobs (right), an associate professor of Earth Sciences in SMU’s Dedman College and director of the Environmental Science and Studies Programs, is part of an international team of researchers hunting scientific clues to Africa’s prehistoric ecosystems.

The researchers are among the first to combine independent lines of evidence from various fossil and geochemical sources to reconstruct the prehistoric climate, landscape and ecosystems of Ethiopia in particular, and tropical Africa in general for the time interval from 65 million years ago – when dinosaurs went extinct, to about 8 million years ago – when apes split from humans.

While it’s generally held that human life began in Africa, ironically there is little known about changes in the continent’s vegetation during the time when humans were evolving.

The multi-disciplinary team is studying fossils they’ve found near Chilga, a small region in the agricultural highlands. Their work will also help climate scientists trying to model future global warming by providing data from the tropics that up to now did not exist.

Contrary to the common notion that vegetation decomposes in the tropics too quickly to supply evidence, sediments there have preserved an abundant variety of 28 million-year-old fossils. These include fruits, seeds, leaves, woods, pollen and spores, Jacobs says.

“There are lifetimes of work to be done in Africa on plant fossils alone, and certainly a lot more to be done with vertebrates as well,” says Jacobs, who’s done research in Africa since 1980 in Kenya, Tanzania and Ethiopia. “There’s not a well established record of plant fossils, so there’s no real context. It’s all new – so whatever you find is interesting.”

Read more from the SMU Research blog

By | 2009-10-06T12:31:00+00:00 October 6, 2009|Categories: Research|Tags: , , , , |

Calendar Highlights: Oct. 4, 2007

Landscape photo by A.E. ByeBye-bye, Bye:The Photography of Landscape Architect A.E. Bye” (top right) begins its final week in the Hughes-Trigg Student Center’s Pollock Gallery. The exhibition ends Oct. 13. Gallery hours are 11 a.m.-5 p.m. Monday, Tuesday, Thursday and Friday, and 1-5 p.m. Saturday. For more information, call the Gallery at 8-4439.

A long view of climate change: The SMU Faculty Club presents Bonnie Jacobs, chair of SMU’s Environmental Science Program, discussing “Climate Change as Viewed From the Past” in its Clubhouse Lunch Series at noon Oct. 9 in the Faculty Club.

Local hero: Author Herb Robertson previews his new book on Everette Lee DeGolyer with a lecture, “The ABCs of De,” Oct. 9 in DeGolyer Library. The event begins with a 6 p.m. reception; the lecture takes place at 6:30 p.m.

Think globally, act locally: The ongoing war and refugee crisis in Darfur, Sudan, provide the focus for “Does Dallas Care?,” cosponsored by SMU’s Human Rights Education Program and Perkins School of Theology, Oct. 9-10 in the Hughes-Trigg Student Center. The symposium is part of three days of events that conclude with Dining For Darfur, in which area restaurants will contribute a percentage of their Oct. 11 sales for humanitarian aid. Find participating restaurants.

Martin Rico's 'Rio San Trovaso, Venice'Venetian finds: To celebrate its recent acquisition of Martín Rico y Ortega’s Rio San Trovaso, Venice (bottom right), the Meadows Museum hosts “Venice in the Age of Impressionism: Rico in Venice,” a three-part lecture series that explores the creative vision and accomplishments of artists working in Venice during the mid-19th to early 20th centuries. Director Mark Roglán discusses Rico’s time in Venice at 5:30 p.m. Oct. 11 in the Museum’s Dr. Bob Smith Auditorium.