The Hawaiian archipelago is a group of volcanic islands in the Pacific ocean. [Fig. 4.1] shows the relative locations of five of these islands. [Fig. 4.1] [Table 4.1] shows the size and age of these five islands and the total number of Mecyclothorax ground beetle species and their species density, on each island. Data for the island of Maui is shown as two distinct regions, West and Haleakalā. This is because they formed at different times from two separate volcanoes. [Table 4.1: island | area / km² | age of island / million years | total number of Mecyclothorax species | species density / number of species per km² - Hawai'i | 10433 | 0.4 | 30 | 0.003; Lāna'i | 364 | 1.3 | 3 | 0.008; Maui (West) | 443 | 1.3 | 27 | 0.061; Maui (Haleakalā) | 1440 | 1.1 | 116 | 0.081; Moloka'i | 673 | 1.9–1.8 | 43 | 0.064; O'ahu | 1545 | 3.7–2.6 | 20 | ...]

1. (a)(i)Complete Table 4.1 by calculating the density of Mecyclothorax beetle species on the island of O'ahu.[1]
2. (a)(ii)Use Table 4.1 to explain why the island of Hawai'i has the lowest density of Mecyclothorax beetle species.[2]
3. (a)(iii)Use Fig. 4.1 and Table 4.1 to suggest why O'ahu has a lower number of Mecyclothorax beetle species than Moloka'i.[2]
4. (b)[Fig. 4.2] shows a ground beetle of the genus Mecyclothorax. All the beetle species of this genus on the Hawaiian archipelago form a monophyletic group, descended from one original colonising species that reached Maui from Australia. The rate of speciation of 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 produced lava flows which cut through ancient forest and vegetation, dividing it into many separate microhabitats. Explain how the large number of Mecyclothorax beetle species on Haleakalā developed.[4]

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