1. Making Ecology a Predictive Science

Little Professor

Professor Tilman was born in the United States in 1949. His home was on the shore of Lake Michigan and he spent his childhood surrounded by nature.

At one year old

At one year old

His loving parents

His loving parents

He liked playing Little League baseball. When he was bored with playing defense in right field, he would wander off to observe nature. His coach called him "Little Professor,"but Tilman did not think he would become a professor.

At Lake Michigan (Left: Tilman)

At Lake Michigan (Left: Tilman)

Encounter with ecology

In his high school days, Tilman loved mathematics, science, and Latin classes. Its science classes emphasized experiments, which taught him how scientific discoveries are done. Around that time, he wanted to become a scientist.

In his high school days

In 1967, Tilman entered the University of Michigan. He had first planned to study physics or mathematics. But in the second half of his sophomore year, he took an introductory biology class that ended with a few weeks of lectures, during which time he fell in love with ecology. It was because ecology asked big questions about life on Earth for issues ranging from evolution and ecosystems to pollution.In his biology class mathematics was used to understand scientific issues. Because Tilman was good at mathematics, he saw ecological research as the best way to use his skills and discover something new.

Tilman had seen Lake Michigan become polluted since his childhood. It was later found to have been caused by eutrophication, and it was not understood scientifically at that time. Tilman wanted to study ecology not simply to acquire knowledge, but also to help solve environmental problems through his research.

Predictive Science

In order to discover or start something new, it is necessary to predict beforehand what may happen. To address environmental problems, Tilman believed it would be important to predict what current environmental problems would be like in the future, including how lake pollution would affect the future lake, from an ecological standpoint.

Tilman decided to study two species of algae that were closely connected to eutrophication in Lake Michigan. He wanted to do an experiment to test if his theory of competition could accurately predict the outcome of competition between species of algae. Up until then, ecologists had only described the already-observed outcomes; none had ever proposed a way to predict, beforehand, which species would win, lose, or coexist when they competed. Tilman wanted to apply his method to predict outcomes.

First, he conducted experiments to clarify which nutrient was required, silicate or phosphate, for algae species A and B to live and reproduce, and discovered the following :

Algae breeding

Tilman further predicted which algae species would win depending on the locations in Lake Michigan, as follows :

  • (1) In the middle of the lake (where silicate is high) Algae species A would reproduce more than algae species B.
  • (2) Near the shore of the lake where rivers add high levels of phosphate Algae species B would reproduce more than algae species A.
  • (3) Between (1) and (2) (where silicate and phosphate levels are almost the same) Algae species A and B would coexist.

In fact, in the competition experiments on algae species A and B in Lake Michigan and in the laboratory, his predictions were proved to be correct. Until that time, most ecological theories simply explained phenomena that had been observed. Therefore, this was the first demonstration that ecology could be a predictive science, and it caused a sensation.

Image of algae experiment

Enjoyed both Research and Life

After earning his PhD from the University of Michigan in 1976, Tilman began working as an assistant professor at the University of Minnesota. Since then, he has been devoting himself to academic research.
He met Catharine, his wife, at university, and they married before he started graduate school. Unlike many researchers, he did not stay in the laboratory from early in the morning to late at night. He also enjoyed time with his family and friends. He loves woodworking, sailing, canoeing, walking in the woods, riding bicycles, and taking photographs. To this day, his personal principle is to keep a good balance between research and life.

2. Rich Natural Environment Produces More

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Prof. David Tilman

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