Bernhard Rensch (21 January 1900–4 April 1990) was a German evolutionary biologist, and ornithologist who did field work in Indonesia and India. He is probably best known as one of the architects of the modern evolutionary synthesis, which he popularised in Germany. His work on the evolution of geographically isolated populations, and on evolution above the species level, contributed to the modern synthesis. He also worked extensively on animal behavior (ethology).
Rensch's education and scientific work was interrupted by service in the German military during both World War I and World War II. His autobiography, published later in life, translates as 'Life of a biologist in a turbulent century'.
In 1929 he published a classic book on species and speciation in which he proposed ideas which later were to become basic principles of taxonomy. He recognised the significance of Moritz Wagner's idea of geographical species-splitting.
In 1947, Rensch published Neuere Probleme der Abstammungslehre: die Transspezifische Evolution. This looked at how the evolutionary mechanisms involved in speciation might be extended to explain the origins of the differences between the higher level taxa. His work contributed to the rapid acceptance of the synthesis in Germany.
- Rensch B. 1979. Lebensweg eines Biologen in einem turbulenten Jahrenhundert. A short memorial was published in Verh. Dtsch. Zool. Ges. 83:673-675 (1990).
- Rensch B. 1929. Das Prinzip geographischer Rassenkreise und das Problem der Artbildung. Borntraeger, Berlin.
- Rensch B. 1947. Evolution above the species level. Columbia, N.Y.
- Mayr, Ernst and W.B. Provine eds. 1998. The evolutionary synthesis: perspectives on the unification of biology, p293–299; p416. Harvard University Press. ISBN 0-674-27225-0.p