Outline7 marksChallenge
The table shows the distribution of beak depth in a finch population before and after a severe drought. Before drought: mean beak depth = 8.2 mm, range = 6–10 mm. After drought: mean beak depth = 9.1 mm, range = 7–11 mm.
Outline how natural selection has caused this change in mean beak depth. In your answer: • describe the type of selection that has occurred • explain how the drought acted as an environmental selective force • state the conditions required for the Hardy–Weinberg principle to apply • explain why these conditions are unlikely to be met in this finch population.