The diagram shows the impact of birds feeding on a population of beetles over time - HSC - SSCE Biology - Question 3 - 2019 - Paper 1

The change in the beetle population can be attributed to environmental pressure. In ecology, environmental pressure refers to the factors that influence the survival and reproduction of organisms within a habitat. In this scenario, the birds are creating selective pressure on the beetle population by predating on them. This means the beetles that are less able to evade the birds will gradually be removed from the population, while those better suited to survive will increase over time. This selective survival leads to a change in the population dynamics of the beetles, demonstrating the concept of natural selection.