[3] He was also known for studying the impact of natural amino acid variation in enzymes of central metabolism on insect flight performance.
[5] In 1955, he wrote to the lepidopterist Charles Remington for advice on a high school science fair project on polymorphism in Colias.
[9][10][11][12][13] Along with Christopher Wheat, he published a paper in 2023 in Science Advances identifying the genetic basis of the 'alba' wing color polymorphism in Colias butterflies.
[17] Biologists Bruce Tabashnik, Joel Kingsolver, Johanna Schmitt, Christopher Wheat, Claire Kremen, Frances Chew, Paul Sherman, Adriana Briscoe, Maureen Stanton, Darren Irwin, Patrick Carter, Benjamin Blackman, Robert Raguso, and Kathleen Donohue were among the students and lab members he trained who went on to have impactful careers in biology.
In 1997 he publicly sparred with Richard Lewontin over advances in the field during a symposium in honor of the 60th anniversary of Theodosius Dobzhansky's book, Genetics and the Origin of Species, held at the National Academy of Sciences Arnold and Mabel Beckman Center in Irvine, CA.
His work on phosphoglucose isomerase (PGI) is a detailed case study of the role of balancing selection in maintaining allelic diversity.