He helped to bridge the divide between the foundations of microevolution developed by the population geneticists and the patterns of macroevolution observed by field biologists, with his 1937 book Genetics and the Origin of Species.
On je pomogao premostiti razliku između temelja mikroevolucije koje su razvili populacijski genetičari i obrazaca makroevolucije koje su promatrali terenski biolozi knjigom Genetika i podrijetlo vrsta iz 1937. godine.