With D. persimilis he found that the caged population followed the values expected on the Hardy-Weinberg equilibrium when conditions were optimal (which disproved any idea of non-random mating), but with a restricted food supply heterozygotes had a distinct advantage.
En D. persimilis encontrou que seguían os valores esperados no equilibrio de Hardy-Weinberg cando as condicións eran óptimas (o cal ía contra a posibilidade de apareamento non aleatorio), pero cun fornecemento de comida restrinxido os heterocigotos tiñan vantaxe.