Blackwell Publishing

The idea of a species - How do we decide between the species concepts?


Two possible conclusions to the controversy between ecological and reproductive species concepts:

• Accept that one or the other of the processes is fundamentally more important. If it were shown, for example, that species of a similar degree of integrity are formed in the absence of gene flow and in its presence, or (on the other hand) that populations diverge in the absence of gene flow even when selection favors uniformity, then the ecological or reproductive concept respectively would be supported.

• Alternatively, we might conclude that both factors work in different degrees in different taxa to produce the kind of phenetic clusters we call species. Some species may be more ecological, others more reproductive. Some biologists have therefore favored a pluralistic species concept, which would explicitly recognize that no single concept accounts for all species.

Even if their relative importance remains undecided, however, we know that interbreeding and selection within adaptive zones are probably the reason why species form phenetic clusters in nature.

The philosopher of science Daniel Dennett gives his own opinion on the controversy.

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