Ernst Mayr

Ernst Mayr (1904–2005) was a German-American ornithologist and systematist whose 1942 book Systematics and the Origin of Species established the biological species concept and placed speciation at the center of the Modern Synthesis. Mayr argued that geographic isolation — allopatric speciation — was the dominant mode by which new species formed, and that this insight required systematists to abandon typological thinking in favor of population thinking. His insistence that evolution proceeds through the multiplication of species rather than the transformation of lineages gave evolutionary biology its organizational backbone for half a century, though recent work on sympatric speciation has complicated his geographic-isolation orthodoxy.