 As with Haldane and Fisher, Dobzhansky's "evolutionary genetics" was a genuine science, now unifying cell biology, genetics, and both micro- and macroevolution.His work emphasized that real world populations had far more genetic variability than the early population geneticists had assumed in their models, and that genetically distinct sub-populations were important.Dobzhansky argued that natural selection worked to maintain genetic diversity as well as driving change.