LAB Unit 2: Ecology Biology II: Mrs. Ireland Name: _______________Period: 1 Date: 2/3 Score: ___/50 QP:___ Survivorship Bubble Lab INTRODUCTION Within a population, some individuals die very young while others live into old age. To a large extent, the pattern of survivorship is species-dependent. Generally, three patterns of survivorship have been identified. These three have been summarized by survivorship curves, graphs that indicate the pattern of mortality (death) in a population. Humans in highly-developed countries with good healthcare services are characterized by a Type I curve, where there is high survivorship until some age, then high mortality. The insurance industry has generated information to determine "risk groups.” The premiums they charge are based upon the risk group to which an individual belongs. While survivorship curves for humans are relatively easy to generate, information about other species is more difficult to determine. It can be quite a trick to simply determine the age of an individual plant or animal, not to mention watching an entire population over a period of years. However, the principle of determining survivorship can be demonstrated in the laboratory using nonliving objects. In this lab you will study two populations of soap bubbles, using them as models of real populations to construct survivorship curves. You will subject the populations to differing amounts of stress to determine the effects upon survivorship curves. OBJECTIVE To simulate a population and demonstrate a survivorship pattern MATERIALS • Bubble solution with wand • Stopwatch Add the objective- conclusion information to page 12 survivorship lab. This is your lab report and is worth a test grade. PROCEDURE Work in groups of four. One person will blow bubbles, a second group member will serve as a timer, a third will observe survivorship, and the fourth will record the data in the table. It is important that group members focus on their “jobs” so your data is accurate. 1. Practice blowing bubbles for a few minutes until they can be generated one at a time with the single end of the wand. 2. Once the bubble is free of the wand, the timer should start the stopwatch. When the bubble bursts, the timer notes the time and the recorder puts a tally mark next to the corresponding age of death on the data table. 3. Obtain data on 20 bubbles for each of these populations: A. Population One: Once the bubble leaves the wand, group members EXCEPT THE TIMER wave, blow, or fan in an effort to keep the bubble in the air and prevent it from dying. B. Population Two: Group members DO NOTHING to interfere with the bubble or to keep it in the air. 4. Summarize your data as follows: A. Record the total number of bubbles that died for each age. B. Determine the number that survived for each age and record. C. Calculate the percentage that survived for each age. Use the following formula: Percentage surviving = Number surviving X 100% to this age 20 D. Graph the percentage surviving. Use the same graph for both populations; you’ll need to use two different colors when plotting the data points. When graphing results, the dependent variable is always placed on the Yaxis. Don’t forget to label your axes and your lines! Results: Graph population one and two on the provided graph paper. Be sure to use a key to denote the two different populations. POST LAB QUESTIONS: add to your conclusion! 1. Which type of survivorship curve does Population One resemble? 2. Which type of survivorship curve does Population Two resemble? 3. How did the different treatments that Populations One and Two were subjected to affect the shape of the curves? 4. What type of reproductive strategy (K or R) would you expect Population One to have? Explain. 5. What type of reproductive strategy (K or R) would you expect Population Two to have? Explain. 6. What are your constants in this lab? Identify at least 3. 7. What is your control in this lab? 8. What is your independent variable in this experiment? 9. What is the dependent variable in this experiment?