University of Mary Washington Species Diversity Worksheet

Write-up: Use the full class data for your Figures.

1. Use island biogeography theory to form good scientific hypotheses for each of the following questions. Remember that good hypotheses are testable explanations for an observation.

• How will the species diversity under large items differ from smaller ones?
• How will the species diversity under isolated items differ from more-connected ones?
• How will the species diversity and trophic habits of animals in “under log” samples differ from “open” samples?

2. For two samples, __CH1c____ and_____TS2c_, show how you’d calculate S and H’. Compare your results to the values your instructor calculated for those samples. The following example should help: Suppose our samples contained 400 individuals in 10 species, and that taxa 1 through 10 were represented by 100, 80, 53, 41, 35, 33, 29, 14, 9 and 6 individuals, respectively.

Table 1: Sample calculation of Shannon index (H’)

3. Figure 1: Plot the relationship of the Shannon index (y-axis) versus the area of cover item for each sample. For this and the other figures, you can plot the “under log” and “open” samples as different plots, or as two data series on the same plot.

4. Figure 2: Plot the relationship of the Shannon index (y-axis) versus the “isolation” (distance from nearest cover item) for each sample.

5. Figure 3: Make dominance-diversity curves for “covered” and “open” samples. Place the log (Abundance) for each species on the y-axis, and the species’ rank in terms of abundance on the x-axis. To make this plot, you’ll first have to sort the data with the most common species first and the rarest species last.

6. Do Figures 1 and 2 support the predictions from island biogeography theory (see #1A and #1B)? Explain.

7. Do the data in Figure 3 support your hypothesis in #1C? Describe the ecological reasons (not methodological or error) why you think the dominance- diversity curves are different (if they are) for “under log” and “open” samples. Be sure to compare both the richness and evenness of the samples. Consider things like: degree of isolation from similar habitat, rate of desiccation of habitat, abundance or lack of food, abundance or lack of predators, abundance or lack of plants, etc. Be specific and refer to the names of actual taxa, rather than generalizing over all species. Spiders are very different ecologically from roaches!