He is the founder of Numerical Ecology, which is a quantitative subdiscipline of community ecology, with his brother the oceanographer Louis Legendre.
Pierre Legendre obtained an MSc in zoology from McGill University in 1969, and at age 24, he earned a PhD in evolutionary biology from the University of Colorado in 1971.
From 1971 to 1972, he worked as a postdoctoral fellow at Lund University.
He has been listed as a Web of Science Highly Cited Researcher in Ecology/Environment in all lists that have been published to this day: in 2001, then from 2014 to 2019 .
His Hirsch index (h) is 76 on Web of Knowledge, which does not count the citations of his books, and 106 on Google Scholar, which includes these citations.