There is considerable variation in the ecosystems that occur in the continent of North America. These include coniferous forest, prairie grassland, scrub and desert. Large areas of land that once contained natural ecosystems are now used for agriculture.

1. (a)Explain how the variation in ecosystems in North America contributes to biodiversity.[4]
2. (b)(i)State the null hypothesis for a statistical test comparing the data from the two types of site.[1]
3. (b)(ii)State how many genera and how many species of beetle are shown in Table 8.1. genera species[1]
4. (b)(iii)Simpson's Index of Diversity for the beetles on the grassland grazed by cattle was calculated as 0.521 using the formula: D = 1 − (Σ(n/N)²) n = number of individuals of each species present in the sample N = the total number of all individuals of all species Calculate Simpson's Index of Diversity for the beetles on the grassland that was not grazed. Complete Table 8.2 to show your working. Show all working to three decimal places. Write your final answer on the dotted line. Table 8.2 species | number on grassland not grazed | n/N | (n/N)² Onthophagus pennsylvanicus | 6641 | | Canthon ebenus | 774 | | Canthon pilularius | 108 | | Onthophagus hecate | 85 | | total | 7608 | | Simpson's Index of Diversity =[3]
5. (b)(iv)Describe what the results in Table 8.1 and both figures for Simpson's Index of Diversity show about the effect of grazing on the diversity of dung beetles.[2]