Professor Clarence Lehman wrote the book on quantitative ecology, literally.

But when Lehman published “Quantitative Ecology: A New Unified Approach” back in 2019 – alongside the University of Minnesota Libraries Publishing and co-authors Shelby Loberg and Adam Clark – he never expected the reach it would have.

Since publication, it’s been viewed over 20,000 times and downloaded over 15,000 times. The majority of readers are abroad, almost 12,000.

“We published that book through the library, and that’s all over the world now,” said Lehman, an adjunct faculty member at the College of Biological Sciences. “They made this book available to the world for free, and that’s the way to do it.”

One of those readers was 24-year-old Solomon Freeman from Assin Tabil, Ghana. He’s a master’s student at Kwame Nkrumah University of Science and Technology (KNUST), studying to become an ecologist.

“I’ve always loved animals, mostly from watching cartoons and catching butterflies,” Freeman said.

Money’s tight being a self-funded graduate student, so Freeman turned to the Internet for open-source materials and found Lehman’s textbook.

“It was so comprehensive and really cool. I would read a page and just think deeply for a while … It is by far the best textbook I have ever read,” Freeman said.

Freeman later emailed Lehman to thank him for writing the textbook, which had helped him succeed in one of his classes. “I wasn’t expecting a reply, and Professor Clarence replied,” he said.

The two struck up a correspondence and have been meeting regularly over Zoom, chatting about everything from Freeman’s ecological research to weather differences between Minnesota and Ghana (the average temperature there is 97 degrees, so Freeman has never seen the snow).

Lehman has become a technical advisor for Freeman’s thesis project, a study of cannibalistic fish. As Freeman explained his work, Lehman realized that this research hadn’t been done quite this way before.

“I don’t think he knew this was new until he showed it to me, and we started thinking about it,” Lehman said. “He’s expanding the field of ecology.”

Quantitative ecology has a lot of models to explain relationships in the animal kingdom: predation and parasitism (what ecologists call a +/- relationship), competition (-/-), mutualism (+/+), commensalism (+/0), amensalism (-/0), and neutralism (0/0).

In predatory relationships, there are wolves and sheep, sharks and minnows, hunters and hunted. The sheep can’t eat the wolf; you’re either one or the other. But Solomon noticed that these cannibalistic fish are both predator and prey, what they’re calling “reciprocal intraguild predation.”

“The classic equations of quantitative ecology typically do not take that into account,” Lehman said. “It’s going to be very interesting to analyze the equations.”

When the dynamics of reciprocal intraguild predation are fully pinned down, researchers will be able to see how these populations might change under different circumstances. Would it morph into a traditional predation relationship or competition, or something beyond?

“How can this system be used to expand knowledge on cannibalism in intraguild predation and community-level cannibalism theory?” Freeman said.

“How can this model be stabilized to determine what affects the region of coexistence between all the species involved? How can we use this knowledge to design novel aquaculture systems that rely mostly on intraguild predation?”

A new approach to textbooks

This isn’t the first time Lehman has received international feedback for “Quantitative Ecology: A New Unified Approach.” It was one of the first open-access textbooks published by UMN Libraries and remains one of the most popular.

“It really speaks to the reach that all these open textbooks can have, that maybe they even have a bigger reach than a traditionally published textbook because they’re freely available,” said Shane Nackerud, director of Affordable Learning and Open Education at the Libraries.

“It would be better for not just the University of Minnesota but universities all over the place if we were all building these materials and working with each other to build up textbooks in all sorts of subjects,” he explained.

Developing and writing textbooks sprung naturally from Lehman’s teaching. In fact, he’d started working on “Quantitative Ecology: A New Unified Approach” before UMN Libraries got involved.

Lehman recorded his lectures, and co-author Shelby Loberg got a grant to hire a copyeditor and turn those recordings into written English. Then Loberg did a first-pass edit and sent it off.

“Shelby was very good at everything, and she fixed it up … the whole thing was her idea in the first place,” he said.

Lehman refined and organized it into chapters, and suddenly they had a draft of the textbook. The writing portion of the process only took three months.

Lehman has continued this with upcoming textbooks. For his next textbook, “Exploring the statistical without all the mystical,” currently in development, rounds of editing came directly from his students.

Instead of using slides, Lehman went through the textbook with his students during class and told them to give honest feedback. For one chapter, his students didn’t understand it all, so he completely rewrote it.

“Had I been working on my own, I wouldn’t have known that,” he said.

From the start, Lehman wanted to publish the book through UMN Libraries. Traditional textbooks are too costly and too difficult to access, he said, but now it’s been distributed across the world.

“Free materials can be customized to meet the instructors’ needs, and they’re better for students because they don’t have to pay for them,” Nackerud said. “That’s the beauty of open education, is that these works can live on and be used and reused and remixed and redistributed.”

Currently, Lehman is working on a second edition of “Quantitative Ecology: A New Unified Approach,” once again using student feedback. For extra credit, or “extra learning” as he calls it, Lehman suggests that students review a chapter from the textbook and explain how it could be updated.

“So now you’re not just helping yourself, you’re helping future students,” he said. “Quite a few students have done that. They often find little things, important things.”

A second edition also gives them an opportunity to improve some of the PDF accessibility and readability elements that weren’t standard practices in 2019, and include examples in a new flexible-syntax readily understandable programming language for the modern era.

“It’s wonderful what the Libraries are doing, and it’ll be interesting to see where we go from here,” Lehman said.

In the meantime, Lehman and Freeman are continuing to meet in preparation for his thesis defense and finding new ways to understand the natural world.

“Professor Clarence knows so much, and he is really considerate. He is always willing to help me out, and he’s constantly looking for ways to improve this project,” Freeman said. “He tells the best jokes too. Honestly, if I can describe him, I would call him a father. I learned how to schedule my day from him and how to follow my passion.”