Species: author definitions.

For a long time the definitions of species have been mainly restricted to l ogicians and philosophers; with the contribution of biologists, the number of concepts increased dramatically The concepts elaborated by authors of th e evolutionary synthesis seemed decisive for a time but the number of defin itions proposed was never as high as in the last half century. In the prese nt review, a list of classical or less well-known definitions are proposed with some commentaries. (C) 2000 Academie des sciences/Editions scientifiqu es et medicales Elsevier SAS.