He earned his Bachelor of Science degree in zoology in 1971 and his PhD in ecology in 1976 at the University of Michigan .
Tilman ( born Titman ) was born in Aurora , Illinois in 1949 .
Tilman earned Tilman 's Bachelor of Science degree in zoology in 1971 and his PhD in ecology in 1976 at the University of Michigan .
Tilman ( born Titman ) was born in Aurora , Illinois in 1949 .