The collapse of the two-kingdom system, the rise of protistology and the founding of the International Society for Evolutionary Protistology (ISEP)

This paper provides a brief summary of the rise and acceptance of protistology as a modern, realistic approach to the evolutionary relationships and classification of unicellular eukaryotic organisms as well as the origins of the multicellular groups. The apparent reasons for the renaissance of this 19th-century concept in the 1970s are reviewed, with electron microscopy considered to be the key factor, strongly reinforced by molecular phylogenetic studies in the 1980s and 1990s. The foundation of the International Society for Evolutionary Protistology in 1975 accompanied this major alteration in the view of biological diversity. The current status of protistology relative to protozoology and phycology is discussed.