Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

This popular objection is again untrue.To begin with, it is necessary to clarify what we mean by the formation of a new species.A great many breeds of dogs have been bred over a time period of the order of hundreds of years.In their phenotype, they differ to such a degree that, if a paleontologist were to discover their skeletons, he would not hesitate a moment to assign them to different species or even genera.Nonetheless, we do not consider them to be separate species because they can interbreed.The formation of a new species amongst sexually reproducing organisms is considered to occur when a reproduction barrier is formed that prevents interbreeding between the members of the old and new species.We have repeatedly been witness to the formation of such a barrier in nature and in the laboratory.For example, it is sufficient for two lines of drosophila to be infected by different strains of bacteria of the Wolbchia genus so that they are no longer capable of interbreeding because of the “cytoplasmatic incompatibility” of their members (see XXI.5.4).Similarly, for example, if cholchicine is used to derive a tetraploid plant from a diploid plant and the former is propagated vegetatively, both the tetraploid and diploid plants will be capable to interbreed; however, frequently it will not be possible for the diploid plants to interbreed with the tetraploid plants.Simultaneously, tetraploid plants frequently have very different phenotype than diploid plants and also differ in their ecological requirements – thus they comply with both criteria for a separate species – i.e. they have a new phenotype and are reproductively isolated.If we really wanted to create a new species of dog, it would actually be possible.It would be sufficient to imitate extinction speciation (XXI.2) and kill off all breeds of dogs except St. Bernard’s and Chihuahuas...