Moritz Wagner - Wagner's Significance in Evolutionary Biology

Wagner's Significance in Evolutionary Biology

Wagner's early career was as a geographer, and he published a number of geographical books about North Africa, the Middle East, and Tropical America. He was also a keen naturalist and collector, and it is for this work he is best known among biologists. Ernst Mayr, the evolutionist and historian of biology, has given an account of Wagner's significance.p562–565. However, others disagree with this account. During his three years in Algeria, he (amongst other activities) studied the flightless beetles Pimelia and Melasoma. In these genera, a number of species are each confined to a stretch of the north coast between rivers which descend from the Atlas mountains to the Mediterranean. As soon as one crosses a river, a different but closely related species appears.

Wagner made similar observations in the Caucasus and in the Andean valleys, leading him to conclude, after the Origin of Species had been published:

"... an incipient species will only when a few individuals transgress the limiting borders of their range... the formation of a new race will never succeed... without a long continued separation of the colonists from the other members of their species."

This was an early description of the process of geographic speciation by means of the founder effect. Another formulation of this idea came later: "Organisms which never leave their ancient area of distribution will never change".

Wagner's idea met with a mixed reception. "Unfortunately, Wagner combined with some peculiar ideas on variation and selection" (Mayr). The leading evolutionists (Darwin, Wallace, Weismann) attacked Wagner's idea of geographic speciation, and it suffered a long decline until in 1942 it was reintroduced by Mayr. The importance of geographic speciation became one of the core ideas of the evolutionary synthesis.