XX.4 Several definitions of species attempt to draw the boundaries of species emerging and disappearing in the course of evolution

All the previous definitions of a species attempted to mutually delimit species existing simultaneously in nature, i.e. at a single time level.However, species exist in time.At a certain moment each species emerges and, at a different moment, disappears; some species exist simultaneously, while others change over time.None of the above definitions can be used to delimit the boundaries of species in time and it is necessary to employ definitions of evolutionary, cladistic or phylogenetic species.

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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.