The Hawaiian archipelago comprises a chain of volcanic islands in the Pacific Ocean. Fig. 4.1 displays the relative positions of five of these islands. Table 4.1 gives the area and age of these five islands, together with the total number of \textit{Mecyclothorax} ground beetle species and their species density on each island. For Maui, the data are presented as two separate regions, West and Haleakalā, because they formed at different times from two different volcanoes. Fig. 4.2 shows a ground beetle from the genus \textit{Mecyclothorax}.
(a(i))[1]
Complete Table 4.1 by working out the density of \textit{Mecyclothorax} beetle species on the island of Oʻahu.
(a(ii))[2]
Use Table 4.1 to explain why the island of Hawaiʻi has the lowest density of \textit{Mecyclothorax} beetle species.
(a(iii))[2]
Use Fig. 4.1 and Table 4.1 to suggest why Oʻahu has a smaller number of \textit{Mecyclothorax} beetle species than Molokaʻi.
(b)[4]
The rate of speciation of \textit{Mecyclothorax} beetles on the slopes of the volcano Haleakalā, on Maui, is the highest recorded for any genus or location on earth. The volcano last erupted 400 years ago. This created lava flows which cut through ancient forest and vegetation, dividing it into many separate microhabitats. Explain how the large number of \textit{Mecyclothorax} beetle species on Haleakalā developed.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Oʻahu frequency = $0.013$” …