THE EVOLUTION OF THE SPECIES CONCEPT, FRO M CUENOT UNTIL TODAY

In the mind of CUENOT, species borders were somewhat arbitrary. lie de fined species both as distinguishable units and as lineages of related organisms. The biological definition of species, however, developed b y DOBZHANSKY and MAYR during the last years of CUENOT's life, was excl usively founded on potential interbreeding ability of natural populati ons, without any reference to diagnosis, and was thought to he objecti ve. Though this concept is still accepted by many evolutionists, it is clear that it does not apply to all situations, for instance that of exclusively uniparental organisms, or that of entities between which r estricted gene flows occur in natural conditions. For this reason, som e new definitions have been recently proposed. In our mind, one of the more significative advances is the cohesion concept introduced by TEM PLETON, while the cladistic concepts are, rather surprisingly, very co nvergent with CUENOT's point of view, half a century later.