@ Dr. Heinz Lycklama
Grant’s Experiments in 1970’s
nGrant’s observations:
nDrought reduced the
availability of seeds, resulting in a 15% reduction of the one island’s
medium ground finch population
nSurvivors tended to have
slightly larger bodies and beaks
nNatural selection
favored those birds capable of cracking the tough large seeds that remained
nThe average beak depth
increased about 5%