Systematics and the Origin of Species
Cambridge, MA: Harvard University Press, 1999. 372 pages.
Systematics and the Origin of Species, published in 1942 and reissued, with a new introduction, in 1999, is widely regarded as largely responsible for the crowning achievement of the Modern Synthesis: demonstrating the compatibility of the evolutionary patterns and processes to be found in natural populations with Darwinian natural selection and Mendelian genetics. It also introduced the biological species concept, according to which species are "groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups." Perhaps the most distinguished evolutionary biologist of the twentieth century, Ernst Mayr was a member of NCSE; he died in 2005, at the age of 100.