In horned beetles, those male with long horns and those males without any horns have an adaptive advantage over those males with intermediate horns. This is an example of directional selection stabilizing selection intrasexual selection intersexual selection diversifying selection 6. Gene frequencies, especially in a small population, can shift randomly and by chance. This is called genetic drift adaptive radiation artificial selection convergent evolution random mating 8. In a population that is in Hardy-Weinberg equilibrium, the frequency of the a allele is 0.2.
Fossil evidence indicates that horses have gradually increased in size over geological time.
This demonstrates the result of convergent evolution stabilizing selection directional selection sexual selection diversifying selection 10.