Paul Jaccard

Paul Jaccard was a professor of botany and plant physiology at the ETH Zurich. He studied at the University of Lausanne and ETH Zurich. He continued studies in Paris with Gaston Bonnier. He developed the Jaccard index of similarity and published it in 1901. He also introduced the use of the species-to-genus ratio in biogeography. In the 1920s, Paul Jaccard engaged in a dispute with the Finnish botanist and phytogeographer Alvar Palmgren over the interpretation of species-to-genus ratio, as evidence of competitive exclusion or attributable to random sampling.