Figure 5.7 Reconstructed phylogeny of African antelopes. Two lineages diverged 6-7 Ma, the slowly evolving impalas and the rapidly speciating gnus and hartebeests. The second group could be said to be evolutionarily more successful than the first, and this might be interpreted as a result of species selection of species-level characters - the rate of speciation. However, the gnus and hartebeests have more specialized ecological preferences than do the species of impalas: perhaps selection has occurred at the individual level (natural selection), and this has had an effect at the species level. Species numbers 14 and 26 are omitted in this study. (Based on Vrba 1984.)
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