How do Environmental Changes affect a Population? Online Lab Name: Date: Open up the website http://www.campbellbiology.com Select the orange edged book, and enter milliga9@msu.edu as the login name and pearly31 as the password. From the pull down menu select Chapter 1: Exploring Life (probably already showing). Under the section Concept 1.4, Investigation: How do Environmental Changes affect a Population? Read the information that is in the upper right quadrant of the screen and follow its directions. You will be able to type in data directly in the Lab Notebook and answer the Question in the boxes given, but make sure you enter all information on this sheet to keep in your binder. (The lab notebook is at the end of the questions.) Lab Report These are the questions you are asked to answer as you go through the lab. Your lab notebook begins after the questions (page 3). 1. What role does genetics play in the variation seen in this leafhopper population? We see variation in the size (small, medium and large) and body color (black and brown) of the leafhoppers. These are two traits that are controlled by genes. The environment can favor one trait over the others, which would lead us in to natural selection. 2. Note the results from the 20th generation under global warming conditions. Before continuing with the 30th generation, predict the population composition of the 30th generation. Possible prediction: All or almost all of the leafhoppers will be small. 3. What happened to the proportion of each type of leafhopper in subsequent generations under global warming conditions? Suggest a reason why the traits of the 30th generation make this population better adapted to its altered environment. -The size of the leafhoppers decreased over the 30 generations. - Smaller body size may be an advantage in warmer temperatures since they may require less food and a small body size helps them to regulate body temperature more easily (stay cooler easier) 4. Why would you expect a change in predators to cause a difference in the types of leafhoppers being selected? A new predator may prefer a different color of leafhopper (they may see colors differently). can affect how much (or how little) a predator must eat to be satisfied. 5. Note the differences between the parental, 10th and 20th generations when the predator changed from a bird to a snake. What evidence supports the view that leafhopper size is not affected by a change in predators? In the later generations we see relatively the same number of large and small leafhoppers. Since their numbers remain the same, we know the change in predators hasn t affected the size of the population. We could also phrase it this way: A change in predators did not affect the size of leafhoppers seen after the 20 th generation.
6. What happened to the proportion of each type of leafhopper in subsequent generations when the predator changed from a bird to a snake? Suggest a reason why the traits predominant in the 30th generation make this population better adapted to the change in predators. The number of black leafhoppers descreased. It is possible that the snake can not see the brown leafhoppers as well as the black leafhopper and therefore don t eat them as often. 7. Describe some human activities around your school that could have influenced the natural vegetation in the area. Human activities that can influence the type of vegetation include building homes and using pesticide. Building new homes would destroy naturally occurring vegetation (trees, bushes, other plants). Homeowners often use pesticides (or herbicides) to get rid of unwanted weed vegetation. 8. Note the differences between the parental and the 30th generations. What happened to the proportion of each type of leafhopper when the vegetation changed? Suggest a reason why the traits of the 30th generation make this population better adapted to its altered environment. When the vegetation changes, both the size and color of the leafhoppers was affected. Over time, our leafhopper population changed to medium body size and black body color. 9. Identify some major sources of pesticides in your area. Homeowners, factories, government 10. What happened to the proportions of leafhoppers in each subsequent generation when pesticides were added to the environment? Explain why all the leafhoppers were not killed by the pesticide application. When pesticides were added to the environment, the leafhoppers average size increased and the color was predominantly black. It is possible that some of the leafhoppers had a gene that made them resistant to pesticides. It they had the gene, they would survive the environment change and then pass that gene on to their offspring.
Lab Notebook Global Warming Data Table possible data 10 th 0 20 5 25 0 20 th 0 10 15 25 0 30 th 0 3 22 25 0 Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE SIZE DATA! Include a title, Predator Change Data Table 1 22 2 22 3 10 th 1 23 1 15 10 20 th 1 23 1 10 15 30 th 0 25 0 2 23 Graph on next page
Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE COLOR DATA! Include a title, Vegetation Change Data Table 10 th 1 23 1 23 2 20 th 0 25 0 24 1 30 th 0 25 0 25 0 Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE COLOR DATA! Include a title, and labels! key,
Pesticide Application Data Table 10 th 5 20 0 24 1 20 th 10 15 0 25 0 30 th 23 2 0 25 0 Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE SIZE DATA! Include a title,