Dobzhansky, an emigrant from the Soviet Union to the United States, and a postdoctoral worker in Thomas Hunt Morgan's fruit fly lab, was one of the first to apply genetics to natural populations. He worked mostly with Drosophila pseudoobscura. Genetics and the Origin of Species "was a key step in bridging the gap between population geneticists and field naturalists. It presented the conclusions reached by Fisher, Haldane, and especially Wright in their highly mathematical papers in a form that was easily accessible to others. It also 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^{" ( Wikipedia article on Modern Synthesis, accessed 03-2017).}