You are comparing pollinator species diversity between two categories of roadside community: restored prairies, which have a di

Sample Lab Final Questions

NOTE: Some of these, on the actual lab final, would have Excel files associated with them so that you could do the data analysis. I have NOT included these Excel files with the sample questions, but have included the questions so you can see the kinds of things you could be expected to do. ALSO NOTE: we didn’t do all the same stat tests in the past; I’ve tried not to include any questions on stat tests you didn’t do, but I don’t have a question for every kind of test you DO need to be able to do.

SITUATION I: GENERAL BACKGROUND. Questions 1-8 apply to this situation.

You are comparing pollinator species diversity between two categories of roadside community: restored prairies, which have a diversity of native plants with a diversity of floral shapes, sizes, colors, nectar contents, etc., and areas planted with a single species of plant that produces large, bright red flowers. You take data as follows: from each of five replicates of each kind of community, you obtain 30 samples of abundance of each type of pollinator by doing point counts at 30 randomly chosen points within each replicate area. For each point, you calculate the Shannon diversity index, H. The Excel file “Pollinators” has the following information: values of H from 30 points from one of the prairie sites, and values of H from 30 points form one of the red flower sites; your goal when you analyze data will be to compare the mean diversity between these two sites.

1. (3) State a plausible ecological hypothesis that can be tested with these data.

2. (2) State a prediction of the hypothesis you just gave that can be tested with these data.

3. (1) Your goal is to compare species diversity (a continuous, measured variable) between the two categories of community. What is the name of the appropriate statistical test?

4. (2) The Shannon index of species diversity, H, is a measure of two factors that contribute to species diversity. These two factors are _______________________ and _______________________.

5. (4) The following information on the number of individuals of each type of species is taken from one of the point count points. Use it to calculate the Shannon diversity index for that quadrat (you can use either Excel or a calculator; for either one you MUST show work below to show how you made the calculation to receive credit for it.)

Species Number of individuals

bumblebee 5

sweat bee 40

butterfly 16

hover fly 29

6. (2) Use the data file “Pollinators” to conduct the appropriate statistical test for the information. Save the results on the disk within the “Pollinators” data file. On the test paper, fill in:

(a) The value of the appropriate test statistic ________________

(b) The value of p ______________

7. (5) Choose the ONE of the following types of plot, column graph showing differences in proportion or graph of mean ± standard error, that is most appropriate to illustrate the results of the kind of statistical test you just did, and make this plot in Excel. Give it appropriate axis labels and an appropriate title in the correct location. Save the results on the disk in a worksheet called “Pollinator Graph” within the “Pollinators” data file.

8. (4) Based on your statistical analysis, state the conclusion about the hypothesis you have tested (assuming that your data are reliable), and explain how this conclusion is reached from the statistics.

SITUATION II: GENERAL BACKGROUND. Questions 9-16 apply to this situation. You are interested in studying the importance of water temperature in determining the fecundity (number of eggs laid) in a species of turtle, and then see how this relates to the abundance of turtles. You study turtles in a number of lakes and ponds with different water temperatures. As part of your study, you conduct a capture-recapture analysis of the abundance of turtles in each pond; you consider small turtles (less than 3 cm snout-vent length) separately from larger turtles (greater than 3 cm snout-vent length) because you are concerned that the smaller turtles may harmed more during the capture-recapture process and therefore suffer higher mortality; this would bias your population estimate. The computer file “Turtles” has information on the number of originally marked turtles of each size category and the number of recaptured individuals of each size category.

9. (3) You conduct a capture-recapture study to estimate turtle population size in one of the lakes in your study. You capture and mark 60 individuals; in your second sample, you obtain a total of 50 individuals; of these, 36 are marked. Give the total population estimate; show formulas and work. You may use either a calculator or Excel to conduct the analysis.

10. (5) You are concerned that smaller turtles may have been harmed by the capture-recapture process, and that as a result your estimate was biased. Use the file “Turtles” in Excel to make the appropriate graph to compare the proportions of originally marked individuals of each age class with the proportions of recaptured individuals of each age class. Label axes appropriately and give your graph an appropriate title in the correct location. Save your graph in a worksheet called “TurtleCapRecap Graph” within the “Turtles” file.

11. You continue your study of turtles and decide to determine the distribution of turtle nests around a lake.

(a) (4) State a hypothesis that would predict turtle nests to have an even distribution. Then state a hypothesis that would predict turtle nests to have a contagious (clumped) distribution.

(b) (2) Within 10 randomly selected 20 m by 20 m quadrats, you find the following numbers of turtle nests:

1
1
0
5
0
1
0
1
5
5

These numbers are also in the Excel file "TurtleDistribution" on your disk. Calculate the index of dispersion (I_d) for these numbers. Show your work, either in the space below (if you use a calculator) or save it in the "TurtleDistribution" Excel file.

Lower Critical Value: 3.32

Upper Critical Value: 16.92

Based on your calculated value of I_d and these critical values, state what you conclude about your hypothesis that predicts an even distribution. Then state what you conclude about your hypothesis that predicts a contagious (clumped) distribution.

(d) (5) Make the plot appropriate to compare the actual proportion of plots with each proportion of turtle nests with the expected proportions of these numbers if turtle nests are randomly distributed. Label axes appropriately and give your graph an appropriate title in the correct location. Save your graph in a worksheet called “TurtleDistrib Graph” within the “Turtles” file.

SITUATION III: You obtain a large sample of white crappie collected from a lake that was about to be filled in to build a housing development. You can age individual fish based on growth rings in their scales.

(a) (5) Use the age information presented to make a survivorship curve for the population. Label axes appropriately and give your graph an appropriate title in the correct location. Save your graph in a worksheet called CrappieCurve

Age class Number of individuals

0 759

1 246

2 240

3 231

4 227

5 40

6 0

SITUAIOTN IV: Two species of flower, red clover and partridge pea, occur in equal numbers in an area. You count the number of times bumblebees land on red clover and the number of times they land on partridge pea, and obtain the following information:

Flower Type:	Red Clover	Partridge Pea
Landings:	40	30

(a) (3) Calculate the chi-square test statistic from these data. Show mathematical formulas and steps.

(b) (3) The critical value for the chi-square test you completed is 3.841. Based on the result of your chi-square test, state the conclusion you can make about bumblebee choice of flowers (is it random or do they land significantly more on one type?); state this, with statistical justification, in the format appropriate for a scientific report.

(c) (5) In Excel, make the appropriate plot to compare observed and expected proportions of landings. Label axes appropriately and give your graph an appropriate title in the correct location. Save your graph in a worksheet called BumblebeeGraph.