 During the 1970s and 1980s, his protein-electophoretic work on many fishes, mammals, and birds demonstrated that natural populations are genetically highly polymorphic and that molecular markers can be utilized to address many natural-history topics that previously had been analyzed solely from phenotypic data.He thereby helped to pioneer the fields of molecular ecology and molecular evolution.In 1994, he published "Molecular Markers, Natural History and Evolution", a comprehensive textbook on the application of genetic markers in ecological, behavioral, and evolutionary contexts.