XX.3.2 Buffon’s definition of species considers the ability to reproduce productively to be the criterion of belonging to the same species

Buffon’s concept of a speciesis apparently the oldest definition of a species as a natural taxon (Mayr 1982).According to this concept, the criterion of belonging to the same species is the ability to productively reproduce, i.e. the ability of a pair of individuals of the opposite sex to produce fertile progeny.As soon as the members of two different forms become capable of fertile reproduction, it is necessary to consider them to be members of the same species, even if their phenotypes are very different and they do not cross in nature – for example because their areas of occurrence do not meet.It is apparent that this method of distinguishing species can be employed only for sexually reproducing organisms.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.